I can’t speak for that particular locomotive, but I got my hands on a Hudson with that same set up, and even on O81 Atlas track, you could tell the flanges were fighting it.....
I thought as much, thank you for confirming my suspicions.
Alas, I have no room for curves in the "greater than O-81" category. I'll be on the lookout for a high-rail version then.
Thank you again!