when i talked to him (he is standing in the wrong position, he should be in the glas) the quest says i need to talk to him to escort, but i cant talk to him and he already follows me, i cant finish the quest
Fixed. Belbua now waits inside his glass cell, and the quest goes the way it reads: he tells you his story, you talk to him again when you are ready to leave, and only then does he follow you out. Before, he started following on your first answer while the quest still told you to talk to him, and a Belbua who was following would not talk. He also talks while he follows now, so a group member with the same quest can join the escort and everyone who brings him out gets it done. If the escort is lost or you log out, he goes back to his cell and you can ask him again. Live after the next server update.
A follow-up: the change that fixed this escort also broke it, and every other escort quest with it. The escorted character gave up as soon as you closed its window or took your first step, so if you tried this quest after the last update it will have failed the same way. It is fixed now, and Belbua follows you to the end again, also in a group. Sorry for the trouble. Live after the next server update.