Okay, FMA(B) logics question: if Ed could put Al's soul into the armour by sacrificing his arm, why didn't their mom's soul come back when they tried to bring her back? Also, if they can control what their new creations look like when they transmute something, why didn't she come back looking like a normal human? If you can't answer, I understand, I was just curious if it was explained in any of the episodes or movies..
Hi anon, the first one is explained. Well, sort of. The reason Trisha’s soul cannot be brought back because she is already dead. However, Alphonse is not dead. He was simply “taken”, held by his truth as the payment to enter the Gate of Truth. This is also why Al and Ed’s arm were able to be returned to them. They did not cease to exist, they were just…not with them. In the same vein, Al’s soul was stuck before the gate, but not gone forever, like Trisha’s was, and Ed’s sacrifice was able to bring it back.
Your second question is a bit hard to answer, because I’m not quite sure. I’m sure that Ed and Al had the image of their mother in mind to transmute, but human transmutation just doesn’t work. I assume it’s also cruel punishment bestowed upon them by Truth. You can’t bring someone back from the dead; you can only make someone new. As a form of punishment, I guess, that thing you create is an utter abomination to nature, much like how human transmutation is.