The AskHistorians subreddit seems to have more specialists and more activity (but also more noise) than this SE.
Googling through this meta and that subreddit makes me think the two communities aren't aware of each other.
This site seems to lack expertslack experts, perhaps we can poach some of theirs?
(If nothing else, cross-posting a few of their less inane questions here might push our questions per day into "healthy" territory.)