If its any consolation, even Warmoth finsihed bodies show grain after a while.
There are some tricks here.
First of all - humidity will run you nuts, because wood swells a LOT with humidity, and filler swells at a different rate. The humidity you finish at should be close to how the item will be stored and used.
Then there's the filler itself - these sometimes take forever and a day to shrink in - just like lacquer. They can shrink under your applied finish too.
Ditto - "sealer"
And finally, even your catalyzed finish will shrink with time. If you applied it well, you can level it and rebuff and not look back.... except I'd wait a good long time before doing that, so you dont continue to get shrinkdown.
Three bodies I had Warmoth finish for me, two mahogany, one maple, but all three show shrink in after just a year or so.