Even if using a manual link to Composer the extension should be categorized in Category:Extensions supporting Composer rather than just being added to Category:Extensions_with_manual_Composer_name. The latter category is just a maintenance category. I understand that only extensions in Gerrit have the information added automatically.
Topic on Template talk:Extension
I changed the module to just show "Extensions supporting Composer" in both cases since I do not know how to get lua to print two categories.