KMail behaviour with search folders, unread counts and new mail

My preferred way of working with email is to have server-side rules that sort all incoming email into various subfolders, then manage them via a consolidated view of all unread email (in all subfolders, in all accounts) in a desktop client like KMail.

I’ve achieved something close to what I’m looking for with this:

However, I have questions…

1. Why isn’t the unread count for this search folder (saved as “Unread All”, below) the same as the sum of the unread counts of the four accounts? I left it overnight for any indexing processes et al. to complete.

(I’m aware the count for the unified mailboxes doesn’t come into it - it’s effectively double-counting a small subset of the unread email in the accounts below).

Is it explained by a design feature I’m not aware of or is there a problem there that needs to be run down?

2. Three of the four accounts seem to be keeping in fairly reasonable lock-step with the unread counts on their respective servers. The unread account labelled “hotmail” is permanently off by about 11 (+/- 1, over time). It seems to sometimes not pick up changes of read/unread status from the server (…is the general theme, although the specifics are more complicated; drilling into individual subfolders, there are more differences - some folders with more unread, some with fewer, when compared to the server - they just net off to a difference of 11). This is after F5, Ctrl+F5 (and watching the progress bars in the bottom right for each subfolder tick by and complete). I also tried clearing the Akonadi cache in an attempt to get it to rebuild the picture, but it just recreated the same incorrect one. Is there anything about how it works that might help explain this? The config of the account in question:

and

3. Unread mail currently shows in light blue, normal-weight font. It’s hard to read. How do I change that to e.g. bold & black?

Yes, I rtfm, but didn’t find anything there. I imagine it’s something to do with view → message list → theme, but I couldn’t find anything there that might let me change the way the message list displays.

Trying to migrate to KMail as my daily driver so am hoping I can get some coaching from the community while I get up to speed…