Romantasy long before that was a thing, this film might actually work better as a Superman “Elseworlds” story than its stated “time-travel” explanation. It looks great and Jane Seymour is as taken with Supes as Margot Kidder - but the script is so silly.
There’s some fun to be had here (again particularly if you can pretend that Supes is undercover or under the influence of Mr. Mxyzptlk), but considering that the time travel explanation lacks any internal logic / technical device, you’re counting on a lot belief suspension.
I remember this being on HBO a lot as a kid (mostly because it wasn’t Superman, but it was) and even with a 4K restoration, it still reads as a TV movie.