Is it reasonable to get the university's legal team to advise on an open source licensing issue that affects software developed for research
Your work is important for your supervisors grant.
Your supervisor is employed at said university and thus his grant is important to the university.
The universities legal team deals with legal issues that are important for the university.

Sounds rather clear to me. Furthermore, asking your supervisor or even sending a short "can you help me with such an issue" mail to the legal team takes only a few minutes of their time.
Of course you should clarify who to ask first and not start off with 10 pages of legal "bla" in your first email.

PS: On the other hand, you might get yourself and the legal team in a lot of trouble if you publish something, under the universities name and with your supervisor employed there, without taking care of such issues first.