1. Are you shure you know what happend ?
Knowing Bosnian legal system NO WAY in hell, a 19-teen years old male gonna end up in prison for beeing drunk/high and vandalising. Either he has a (big) court history or he actually did far serious shit (or he is unluckist SOB in the Balkans...and thats not small feat).
...gledaj, s 19 napraviÅ¡ sranje, uhvate te ('beÅ¡ sreću), s 20 dođeÅ¡ kod suca, veliÅ¡ "nisam htio", sudac nekaj diktira zapisničaru 5 min i NE IDEÅ u zatvor...
2. Guards are not a problem (in the way that you think), they simply don't give a shit.
IF your cousin ends up in prison, he is gonna get beaten, badly(by the inmates) - thats 100%. Tell him to get a haircut and tone down his attitude, he'll still get beaten, but not as often and not as badly. Rape is very uncommon (he can shower freely).
As for mixing with a bad crowd, I still can't belive that a 19teen years old male gonna end up in prison for beeing drunk/high and vandalising, if he becomes a criminal he will be "last in the feeding chain". Very bad future.
...of course if your cousin is 2m and 100 kg and has allready friends in prison, disregard writen...
3. To really bail him out and help him would mean to adopt him. (Pay the money, invite him to Germany, start parenting). Thats BIG.
...I would do it for my brother, not so shure about my cousin...
4. Whole thing is apsurd. Resolve the prison thing with papers (hire a lawyer) - something is really fishy there - I think the boy and his mother played their cards VERY badly.
Meet with the guy...face to face...talk with him (you were also wild in his age)...do it a few times...