You are not limited to just string lists. It is choosing what lua file(s) to load. You can have more than one too. It is just doing a string concatenation for the file name before loading.
So, you can use that as part of an incremental rollout step and merge into main when full language support is ready. Or maybe you just want some special feature loaded for a specific language. Using the language variable is a way so the lua code only load for it. This may be fringe cases for most but your suggestion could break the add-on in a different way than just because the end-user is running a ZOS unsupported language. If they want hack to another language, than they can modify the add-on’s manifest manually.
--Halja