Hello @sebastienbeau do you have time to give us a feedback about this?

I don't want to anticipate @sebastienbeau response, but sadly Akretion skipped Odoo 11.0 version entirely (it's quite counter productive to try to be expert in every version) so we easily review PRs against 10.0 and 12.0, but for 11.0 it's much less likely...

@rvalyi @sebastienbeau If you're using this module in v12.0, you might want to refactor this part:
https://github.com/akretion/odoo-usability/blob/12.0/account_invoice_update_wizard/models/account_invoice.py#L12-L21

This was probably done to avoid having the wizard overwrite the changes done manually when calling its action (as create is called from the UI, the values were overwritten by default_get), but IMO the solution here is cleaner.