Heritage (OSI Clone) which is run by the guy (Dan) running ServUO had a lot of issues as well. He fixed them on Heritage but not sure if he moved those fixes to the ServUO package or just Heritage.
From what I have been playing around with here at home with a ServUO server - a few fixes make it into the TrueUO github that is publicly accessible, but even those haven't made it into the ServUO master in a year or more.
I fired up 4 servers: pub57, pub57.1 (a couple fixes there, but the content is too old for my goals), servuo-master and trueuo. At the moment I have my version of servuo-master running the best so far. Pub57 had a few things that were functional which are broken in servuo-master. I have made it through making all of TerMur and Stygian Abyss dungeon fully functional and have a checklist for the steps documented to get to that point.
TerMur/SA do not work to decorate or even have complete spawn in servuo-master (entrance quest doesn't function even), while trueuo has the entrance quest functional, but for claiming to be OSI compliant - they changed the quest questions and answers, but the world populating has all the same errors of servuo-master. So from my standpoint, I do not think much from Heritage makes it back to servuo-master in the past 1-2 years.