I found a site. If this is from a textbook, I'm not sure I should link to that site, but it's not all that hard to find (it or one like it). I'll just lift the relevant parts.
The entire context seems to be this ("Q" and "A" added for clarity):
Q: What is relevant to someone's judo skills?
A: Though it is called skill, whether a person is good or bad at judo is not the only factor; the attitude of the person employing those skills is also important.
That's the meaning. Nuance...?
Xといっても kind of means "it's kind of X, but not entirely what X immediately implies".
問題 has a meaning of "something that needs to be discussed", so I took that as "relevant". But a more standard translation of 問題 that fits that same sense is "issue", so you might also think of the question as "What is at issue in" or "What is an issue for". For what it's worth, alc's results for 問題にして(いる) suggest "concern" or "worry"...arguably, "important", but those are also with people as the subject, not judo or some such, as here (although, as you may note by the switcheroo from "what is relevant" to "is also important", "relevant" and "important" are fairly close).