Just because there were 8,000 block changes does not mean they were all made by him, Anth. He could have just placed a few and the rest of the changes could have been something like from clearing Land or making another building. It could have been a large variety of things that made it say 8,000 block changes. Just keep that in mind.
I know this is locked but there is one thing that needs to be make clear. When you do a lb rollback, it goes from bedrock to sky limit. This means if medik has a mine underneath newhaven, that’ll get rollbacked as well.
Stand where you did the rollback and run this command (replacing time with whatever you did)
/lb lookup player Medikherb area 50 since {time}
This will show you every block change that was affected. As I didn’t know where the rollback occoured, I have no way of telling what blocks were modified, but I’m pretty sure most of them will be underground.