It seems like you can do TSW2020 Mastery on TSW2 now. TSW2 shows me the Mastery Challenges for MSB, Lirr, NTP and GWE right now. But It's a little Buggy
Actually it's new TSW2 Mastery. It's a pity though that all we get are little impossible-to-find little scenery tiles, instead of TSW2020's dioramas.
Yes, I'm really glad to see the routes that had mastery in 2020 get mastery in TSW 2, and I think the livery designer decals are quite nice, but I would have also loved to see the dioramas come over to TSW 2 mastery as well. And given that Yuri made an LIRR diorama port mod for TSW 2, it should be easy enough for DTG themselves to bring it to TSW 2. I do hope we see them get added later in the future. Especially since mastery could really do with some bulking up in terms of the challenges you complete. 2, and even 1 on Clinchfield, isn't that rewarding, since they are relatively easy to do with small rewards. If there was another tier or two, with the last tier being a diorama, then I think that'd make mastery quite a bit more rewarding, at least in my opinion.