demm Think enforcing English only is the best way actually. I assume that KaOS have lots of uses around the world, speaking different languages. The forums would be unusable if everyone decided to use their native language, big or small ones (speak Swedish myself).
The second problem is that it's impossible to search for anything written in other languages, witch could mean that solved issues won't be found for other users. Using an online translator is not just good enough.
I hang around a lot on XDA Developers also, and they have a strict English only policy.
We understand that with all the different nationalities, not everyone speaks English well, but please try. If you're really unable to post in English, use an online translator. You're free to include your original message in your own language, below the English translation.
I think their approach is very acceptable, if you write in your native language you must include an English translation to it so everyone knows what's been typed.