As John Brooks said, it is not in the friend's control, he would not be doing the releasing himself but asking customs to do it. If you are asking him if he has succeeded then something like 'Did you manage to get them released?' If you are asking him to try then 'Could you try to get them released'. Either way, 'true' is not the correct word to use in your question. True does not mean the same as correct, it means 'describes reality', so if I were to say 'I is a man' it would be true but not correct, but 'I am a cat' would not be true but would be correct English

Because it sounds like your friend cannot totally control the situation, and can only hope to persuade the customs officials to release the documents, I suggest “Can you try to get them released?” “Try” because it is not totally in his power, “get them released” because he is not actually doing the releasing, but taking steps to get/persuade someone else to release them.