Yes, you should.
How you do that is the key
You are not an expert - or assumed not to be an expert: and the minute you start pointing to what might - or might not - be a problem, you become a target. For his (?) ire.
Raise the issue in plain straight terms:
I see this [...] as a problem. Am I correct in thinking it is one?
How are we going to get to the required level ? And by when ?
Do not suggest an answer to your question(s) - you'd be pissed off with me if I came and asked you why you'd coded that 'class' as you did.
Give clear direction on the desired outcome
Supervise daily - take a benign interest in the short term, tighten as necessary
Under no circumstances pay him yet.