I comment text in both English and German. The (now semi-defunct) feddit.de instance has some/many/most communities that only allow German as language, while on other instances or in communities only English is allowed (or at least that's the only way my comments get posted).

This creates the problem that I cannot really set a default language tag, because that would regularly delete my comments when the comment doesn't get posted with no or the wrong language tag (because I forgot to add or change the tag.

I don't know about programming, but I'm not sure how taxing this would be memory- or caching-wise.