The assistant professor doesn't answer e-mails

15 days ago was the weekend before Christmas, 5 days ago was new years day. I am not surprised the assistant hasn't answered: my university is closed till Monday. Since I have children and the school and kindergarten are also closed till Monday, I have very little time for answering emails. Moreover, this is the time of year to focus on other things than work (why am I writing this answer?).

While there may be exceptions, I think that in most places it would be proper to ask the question of the professor. You could also mention that you haven't yet received an answer from the TA. That might get things moving better in the future.

I would't phrase the comment about the TA as an accusation or complaint; Just the fact that you asked, haven't yet heard back, and need the answer.