They work fine for me - do you have any mods installed? If not, maybe try to validate game files?So custom battles straight up don't work
It seems that the tier 4 Vlandian Swordsmen now have some very weak helmets, which are fairly significant downgrades from the previous tier 3 infantry. I'm not sure if their equipment list changed, or if some items themselves were altered, but I don't recall them having such poor head armor in the past. (In my opinion, one of the Battanian Oathsworn helmets also needs an upgrade, but that's not a new "issue.")
I'm also not able to get any cavalry to perform a couched lance charge in custom battles (haven't tried in campaign/sandbox yet). Sometimes individual soldiers will couch their lances as they cycle through their charges beyond the very first one, but that's about it. Even charging into the rear of engaged infantry with something like Vlandian Banner Knights doesn't result in a couched lance charge.
On a big positive note, it does seem as though infantry fights last a bit longer than before, allowing more time for flanking maneuvers (including with foot skirmishers, which used to be really difficult to do fast enough for it to matter).