Probably not a good fix. There could be different circumstances under which training is undergone. For example, maybe the person went through the training but has yet to summon an aeon. First level of summoner is taken when he/she finally does it. If you remember, Yuna had to try a few times.

Also, the game isn't going to wait for anybody to train for months or years for the sole purpose of taking one level in another class. Remember, first and foremost, this is a game. The game must come before "what makes sense" in this case.