Well that’s the bright side of me having such an inconvenience : I was able to get the support team realize rather quickly that this was a general forums issue (kudos to Zeadom in particular, who caught on fast) 
. So I can only suppose they fixed the issues for the others in the same time.
Yep, now that we know that fixing one doesn’t solves the other, it means that they probably weren’t linked. However, I first thought they were, and also used one of your messages in that thread to prove the technical agents this was a larger issue. So it’s likely that people managing the forum are now aware of the stalled avatars bugs as well. 
Also, dunno if you noticed, but since a few days after the patch 5.0.4 thread, they seem to have fixed the mismatches on the profile websites :
My avatar on the websites is now the Stars’ party, with a 14-14 batch reference :
And Kerrigan (which was previously the 14-14) is now 15-14 :
They also reuploaded the black avatars, as proven by Heromarines 2019’s avatar (8-16) now being displayed instead of the black one it used to be :
Also the missing portraits (which couldn’t be found anywhere), are now available. They were in batch 9 in fact :
So I think the websites team saw the thread, and successfully corrected the mismatches. Thumbs up of them.
So the only issue left to fix is the purely forums one “stalled avatars” bugs (which unfortunately prevents us from benefiting from the fixing of the mismatched avatars lists XD). But they should be aware of it by now, since I presented them the two issues. So maybe its chances to get fixed in the next months did increase a bit.
At worse, we could always get through technical support once again ; but as they just made the effort to fix the login bug I reported to them, I don’t feel it would be fair for me to pressure them about the stalled avatars at the moment. 