Apparently the l10n tooling works better when the comment starts with this kind of formatting:

    "# LOCALIZATION NOTE(compose-invalid-addresses-title): note goes here

Thanks to asuth to recently pointing this out in the [localization notes](https://developer.mozilla.org/en-US/docs/Mozilla/Localization/Localization_best_practices#Add_localization_notes). So for any new strings we should try to match that format.