The Consigliere is one of the strongest roles the Mafia has (their killers aside, obviously.) The gap between them and most other Mafia non-killers is pretty stark.
More than that (and the main reason I'm suggesting this) - the Consigliere severely punishes NKs, since it's effectively another person who will doom you if they find you. That's not something the game needs. Mafia can already find NKs by attacking them, and can beat them by outnumbering them or finding them via elimination in the late game. They don't need a super-investigative capable of flawlessly identifying NKs on sight on top of that.
Therefore, I suggest a change akin to the recent Sheriff change: The Consigliere can still perfectly identify Town, but for everyone else, their results are more limited. There are a few options:
1. The most extreme, Your target is not a member of the Town. No other info. Only problem is that this could in theory make the Consigliere useless in modes with no Town, but this is an oblique enough scenario that I'm not sure it's a concern.
2. Alternatively, if that is a concern, when investigating non-Town, you only learn their faction - Your target is neutral, Your target is a vampire!, or Your target is a member of the Coven. (Plus Your target is a member of the Mafia! if they get redirected or witched.) Possibly they could even learn exact Coven roles; I suspect that makes less difference than it seems. Vampires could also be considered neutral - it would help protect NKs a bit more by giving them slightly more cover, which is the main point here.
I don't feel that the Mafia should have a role that is so effective at finding NKs, since they already inherently have an advantage over NKs as long as they can beat the town without running down to 1 person, and since, realistically, the Mafioso / GF are already very effective at finding NKs by hitting their immunity.
(Now, you might say, wait, in the current Ranked list, there's only one neutral other than the NK! But Ranked isn't the only mode, and 50-50 uncertainty is still waaaay better than being 100% exposed to the Mafia with no doubts at all.)