I don't find this to be true. I "upgraded" to 2.26.0. Right now I have a vFolder. If I look in my Inbox there should be exactly 1 message that matches and it is unread. And indeed under search folders it says 1 unread, but 3 total. If I go into the vFolder then it doesn't list *any* messages, not even the 1 unread one.
I've emptied the trash and even closed/restarted Evolution but no go. Looks like I'll be downgrading back to 2.22.x :-(
As far as attention from users. This is another category I've been disppointed about. I've been submitting Evo bugs for years and usually I don't get any response. Then, 2 or 3 GNOME generations later I finally get a response either asking for more info, for which I don't have because I'm not using that version anymore, or that the issue should be fixed in a more recent version and that I should upgrade. The vFolder count bug has already been reported (I think I'm CCed on it) and I see it's gone through an entire GNOME release without being fixed.