Yes most of ex-yu uses those letters.
All apart from Kosovo and Macedonia. And there are only 2-3 Kosovars on server and they speak English quite well. So yeah, these "palatals" are used all around Ex-yu (Slo, Cro, Ser, Bos, MN). There are no Macedonian players that I know of. Just block the letters and few curses and you've solved the problem of ~15% of lingual rulebreakings.