I have automated most of the pull requests below, to ones where it is indisputable what the License of the project was, either due there only being one LICENSE and it matching copies of those licenses almost exactly, or the metadata for license key was set to something such as "The Artistic License 2.0" or the URL of the Artistic License or something ambiguous and able to be automated.

I am posting this here since I have finished the automated stage and going forward most of the rest will probably have to be checked manually to check what license they actually are (for those that have a LICENSE type file), or for those which don't opening an issue for the project.

• Standard licenses identifiers can be found here: https://spdx.org/licenses/
• The standard identifier for Artistic 2.0 is Artistic-2.0
• For more info see: https://design.perl6.org/S22.html#license which is the primary reference, though see below for the note about Dual Licensing.

Dual Licensing

Though it is not yet in S22, the way to denote a dual license using the SPDX spec is as below:

A license which allows you to use subsequent later versions if you choose

Common with GPL licenses. Example: GPL-3.0+. You can use a + after the license name to denote this. The + syntax is universal, and can technically be applied to any license, though in practice an "or later" clause is most often found in GPL (though please note GPL-3.0 means ONLY GPL-3.0, GPL-3.0 does not imply that you may use any later version).

Example using the licensing of the Perl 5 project, which is dual licensed under Artistic 1.0 as sourced from the Perl site and the GPL-1.0 (or greater):
Artistic-1.0-Perl OR GPL-1.0+

Detailed information about the ones which do not yet have Pull Requests can be seen in this JSON here:
https://gist.github.com/samcv/9177c43f2a78049248fcb954c63d28e5

Note: jonathanstowe has stated he would not like any PR regarding metadata to his projects
This list contains all non-standard identifiers, and a very small number which have no license at all (added manually and not computer generated like the non-standard identifier ones were).

No PR or Issue

• Terminal::ANSIColor (R*)
• Template::Mojo (R*)
• Linenoise (R*)
• PSGI (R*)
• MIME::Base64 (R*)
• Pod::To::HTML (R*)
• rakudo-debugger (R*)
• File::Find (R*)
• Inline::Scheme::Guile
• CompUnit::DynamicLib
• Digest::SHA1::Native
• EventSource::Server
• RPi::Device::PiGlow
• Acme::Insult::Lala
• Archive::SimpleZip
• RPi::Device::SMBus
• Algorithm::Tarjan
• Audio::Liquidsoap
• Getopt::ForClass
• CompUnit::Search
• Audio::PortAudio
• Crypt::TweetNacl
• Hash::MultiValue
• Printer::ESCPOS
• App::ModuleSnap
• Audio::PortMIDI
• Monitor::Monit
• Music::Helpers
• IO::Path::Mode
• Perl6::Parser
• Unicode::GCB
• Doublephone
• Task::Noise
• Pg::Notify
• Log::Async
• Lumberjack
• XML::Class
• Test::META
• Manifesto
• DOM::Tiny
• Clifford
• GraphQL
• ANTLR4
• META6

Outstanding Issue

• HTTP::Request::Supply License field in META file uses non-standard name zostay/HTTP-Supply#2

Outstanding PR

Rejected

Note repeated from above: jonathanstowe has stated he would not like any PR regarding metadata to his projects

• Lumberjack::Dispatcher::Syslog Use SPDX identifier in license field of META6.json jonathanstowe/Lumberjack-Dispatcher-Syslog#1
• PR rejected change from "Artistic" -> "Artistic-2.0" in META. Project has Artistic 2.0 License
• Lumberjack::Application Use SPDX identifier in license field of META6.json jonathanstowe/Lumberjack-Application#2
• PR rejected change from "perl" -> "Artistic-2.0" in META. Project has Artistic 2.0 License
• Test::Util::ServerPort Use SPDX identifier in license field of META6.json jonathanstowe/Test-Util-ServerPort#1
• PR rejected change from "Artistic" -> "Artistic-2.0" in META. Project has Artistic 2.0 License
• MessagePack::Class Use SPDX identifier in license field of META6.json jonathanstowe/MessagePack-Class#1
• PR rejected change from "perl" -> "Artistic-2.0" in META. Project has Artistic 2.0 License
• EuclideanRhythm Use SPDX identifier in license field of META6.json jonathanstowe/EuclideanRhythm#1
• PR rejected change from "perl" -> "Artistic-2.0" in META. Project has Artistic 2.0 License
• Audio::Hydrogen Use SPDX identifier in license field of META6.json jonathanstowe/Audio-Hydrogen#1
• PR rejected change from "perl" -> "Artistic-2.0" in META. Project has Artistic 2.0 License
• URI::FetchFile Use SPDX identifier in license field of META6.json jonathanstowe/URI-FetchFile#1
• PR rejected change from "perl" -> "Artistic-2.0" in META. Project has Artistic 2.0 License
• Audio::Icecast Use SPDX identifier in license field of META6.json jonathanstowe/Audio-Icecast#2
• Util::Bitfield Use SPDX identifier in license field of META6.json jonathanstowe/Util-Bitfield#1
• Tinky::JSON Use SPDX identifier in license field of META6.json jonathanstowe/Tinky-JSON#1
• Oyatul Use SPDX identifier in license field of META6.json jonathanstowe/Oyatul#1
• Tinky Use SPDX identifier in license field of META6.json jonathanstowe/Tinky#3
• Below have not been rejected but are jonathanstowe's modules (moved from section above)
• Audio::Fingerprint::Chromaprint
• Device::Velleman::K8055
• Audio::Playlist::JSPF

Merged or Fixed

• Grammar::Profiler::Simple (R*) Project has no License perlpilot/Grammar-Profiler-Simple#4
• Crust Use SPDX identifier in license field of META6.json tokuhirom/p6-Crust#90
• Readline Use SPDX identifier in license field of META6.json drforr/perl6-readline#18
• Grammar::BNF Use SPDX identifier in license field of META.info tadzik/Grammar-BNF#9
• Operator::defined-alternation Use SPDX identifier in license field of META6.json gfldex/perl6-operator-defined-alternation#2
• Rakudo::Slippy::Semilist Use SPDX identifier in license field of META6.json gfldex/perl6-rakudo-slippy-semilists#3
• Sparrowdo::Cpanm::GitHub Use SPDX identifier in license field of META6.json melezhik/sparrowdo-cpanm-github#1
• Proc::Async::Timeout Use SPDX identifier in license field of META6.json gfldex/raku-proc-async-timeout#1
• Template::Mustache Use SPDX identifier in license field of META.info softmoth/raku-Template-Mustache#18
• Unicode::UTF8-Parser Use SPDX identifier in license field of META.info krunen/unicode-utf8-parser#1
• Slippy::Semilist Use SPDX identifier in license field of META6.json gfldex/perl6-slippy-semilist#1
• Sparrowdo::Rvm Use SPDX identifier in license field of META6.json melezhik/perl6-sparrowdo-rvm#1
• Text::More Use proper SPDX license identifier in META6.json tbrowder/Text-More#6
• Term::termios Use SPDX identifier in license field of META.info krunen/term-termios#7
• LMDB Use std. license identifier and use 'license' not 'licence' key salortiz/p6-LMDB#1
• Bailador Use SPDX identifier in license field of META.info Bailador/Bailador#99
• BSON Use SPDX identifier in license field of META.info MARTIMM/BSON#17
• NativeHelpers::Blob (R*) Use std. license identifier and use 'license' not 'licence' key salortiz/NativeHelpers-Blob#4
• 007 Project has no license masak/alma#224
• DBIish (R*) Use SPDX identifier in license field of META6.json raku-community-modules/DBIish#91
• Text::Markov Use SPDX identifier in license field of META6.json bbkr/Text-Markov#6
• GeoIP::City Use SPDX identifier in license field of META6.json bbkr/GeoIPerl6#12
• TinyID Use SPDX identifier in license field of META6.json bbkr/TinyID#2
• Unicode::PRECIS Use SPDX identifier in license field of META.info MARTIMM/unicode-precis#3
• MongoDB Use SPDX identifier in license field of META.info MARTIMM/raku-mongodb-driver#14
• Auth::SCRAM Use SPDX identifier in license field of META.info MARTIMM/Auth-SCRAM#6
• Pod::Render Use SPDX identifier in license field of META6.json MARTIMM/pod-render#3
• Tinky::Hash Use SPDX identifier in license field of META6.json MARTIMM/tinky-hash#1
• TXN https://github.com/atweiden/mktxn/pull/2
• TXN::Remarshal https://github.com/atweiden/txn-remarshal/pull/2
• File::Presence https://github.com/atweiden/file-presence/pull/2
• Config::TOML Use SPDX identifier in license field of META6.json raku-community-modules/Config-TOML#3
• Digest::xxHash Use SPDX identifier in license field of META6.json raku-community-modules/Digest-xxHash#2
• TXN::Parser https://github.com/atweiden/txn-parser/pull/2
• Crane Use SPDX identifier in license field of META6.json raku-community-modules/Crane#3
• PKCS5 Use SPDX identifier in license field of META.info MARTIMM/PKCS5#1
• Config::DataLang::Refine Use SPDX identifier in license field of META6.json MARTIMM/config-datalang-refine#3
• Semaphore::ReadersWriters Use SPDX identifier in license field of META.info MARTIMM/semaphore-readerswriters#5
• PerlMongers::Hannover https://github.com/paultcochrane/Perl6Mongers-Hannover/pull/3
• Pod::To::BigPage Use SPDX identifier in license field of META6.json perl6/perl6-pod-to-bigpage#6
• Sparrowdo::Rakudo Use SPDX identifier in license field of META6.json melezhik/perl6-sparrowdo-rakudo#1
• PriorityQueue Use SPDX identifier in license field of META6.json hoelzro/p6-priorityqueue#3
• CompUnit::Repository::Panda Use SPDX identifier in license field of META.info niner/CompUnit-Repository-Panda#1
• Linux::Proc::Time Use SPDX identifier in license field of META6.json tbrowder/Linux-Proc-Time#3
• Grammar::Highlighter Use SPDX identifier in license field of META.info niner/Grammar-Highlighter#3
• Net::IP::Lite Use SPDX identifier in license field of META6.json tbrowder/Net-IP-Lite#1
• Number::More Use SPDX identifier in license field of META6.json tbrowder/Number-More#2
• Control::Bail Use SPDX identifier in license field of META6.json skids/perl6-Control-Bail#2
• Proc::Screen Use SPDX identifier in license field of META6.json skids/perl6-Proc-Screen#1
• Inline::Perl5 Use SPDX identifier in license field of META6.json niner/Inline-Perl5#95
• X::Protocol Use SPDX identifier in license field of META6.json skids/perl6xproto#1
• IO::Glob Use SPDX identifier in license field of META6.json zostay/raku-IO-Glob#6
• PackUnpack Use SPDX identifier in license field of META6.json lizmat/PackUnpack#2
• Text::CSV Fix license field in META6.json Tux/CSV#4
• Slang::Kazu Use SPDX identifier in license field of META6.json Altai-man/Slang-Kazu#1
• wig Fixed!
• Net::Netmask Fixed!
• Pod::To::Markdown::Fenced Fixed!