public sealed class TestCommandModule
{
    [Command("test"), Description("[Owner] Command to test random stuff")]
    [InteractionLocalizer<TestInteractionLocalizer>]
    [SlashCommandTypes(DiscordApplicationCommandType.SlashCommand)]
    [InteractionInstallType(DiscordApplicationIntegrationType.GuildInstall)]
    [InteractionAllowedContexts(DiscordInteractionContextType.Guild)]
    [RequireApplicationOwner]
    public static async Task ExecuteAsync(SlashCommandContext ctx)
    {
        await ctx.RespondAsync(ctx.Interaction.Locale);
    }
}

public sealed class TestInteractionLocalizer : IInteractionLocalizer
{
    public async ValueTask<IReadOnlyDictionary<DiscordLocale, string>> TranslateAsync(string fullSymbolName)
    {
        return new Dictionary<DiscordLocale, string>()
        {
            { DiscordLocale.en_US, "test_en" },
            { DiscordLocale.fr, "test_fr" }
        };
    }
}