Thanks for the mention guys.
Hi @meglio – that sounds like a really tricky situation. Cultural differences can definitely be problematic at times! It reminds me of this paper, which probably won’t inform your situation much, but it’s a really interesting read.
I think that your fear of banning (or disciplining) people due to the resulting loss of their knowledge is understandable, but if you’re already losing others as a result of their behaviour then you need to act. Although the cultural aspect makes the lines blurry, you can still have very clear boundaries when it comes to personal comments or insults.
So I’d do this. I’d write my TOS/guidelines so that they are very clear around the use of personal innuendo or insults, and then every time it happens, I’d gently (but publicly) point the person in that direction. That will continue to reinforce the message to the protagonists and also demonstrate to the rest of the community that you are aware of it and are actively trying to solve the issue.
And if it keeps happening, then I’d start banning. There are a lot of knowledgeable people in the world, but if you get a reputation for being unwelcoming, that’s very hard to fix.
I hope that helps a bit. If you’d like to troubleshoot further, we’d love to have you join us at FeverBee (we’re a community for community managers and this kind of issue is right up our alley 
).
Good luck.