A challenge function would be very nice and really should be implemented. It also might help them fix the ladder system. As Wolves, you and Magyar would probably still roll over 87.5% of the "top teams" anyway so you might not notice a huge difference.
I know that is not your only concern-- but the new Avatar and vet system via MM battles is basically still experimental and it is fun, and that is what most people are doing, but you could stick to "Classic Battles" and avoid all of those issues.
Right now my main concerns are (in no particular order) Non-functioning morale penalties (several types), forced 22k for high ranking MM battles (magnifying non-functioning morale penalties), non-functioning retainers and clan token skills, mega-clans being unbeatable in the clan competition (you could win 100% of matches against them as herioc victories and still not even make a dent in their provincial holdings), ALT-F4 droppers (affecting ladder ranking), other ladder bugs affecting ranking (randomly fluctuating ranking).
I haven't seen any rtillery spamming lately so maybe that has been fixed (1 unit max?)-- if not add it to my list.
Then again as long time players we are pretty picky. What's important post 1.3 patch is that the instability of the MP platform itself appears to be fixed. If you play only 10k classic battles with friends, almost none of those issues will affect you. Of course nobody is doing that because the avatar/vet system is so much fun-- but my point is -- for the first time since launch there is a way to play predictably stable MP battles that are essentially bug-free (classic battles only, mind you) and similar in form to prior TW releases. I recognize the classic battles are no longer as exciting as they used to be (with the avatar/vet system) but they appear to be stable now.
Bookmarks