I agree especially with Emily Morehouse’ comment that “[T]he council should adequately fill the integral duties described in the quoted charter from the C++ Direction Group.”
More specifically, I believe that the SC will absolutely require expert advice on many topics. But I also think that expert advice should be focused on specific topics, i.e. on particular PEPs or families of closely related PEPs. I expect that all member of the SC will have a broad technical knowledge, at least enough to know what the right questions to ask are, so the need for additional generalists feels less likely. However, on in-depth matters, we/they would often need to rely on one or more delegates for advice (I suppose now SC-delegate rather than BDFL-delegate).
We already have the delegate role in relation to PEPs, so there is probably overlap between that and this likely new role. But I think that using the equivalent of legal “special masters” is likely to be common (who may well be the person as a PEP delegate). However, as I’ve said, I don’t think that should be a standing role, but one specific to a particular decision process.