Pretty good two levels, Frost!
I'd suggest enabling Friction Fix in Ice Paradise Zone in order to make star boosts not detrimental in it. I'd also strongly suggest using my Speed Pad Storing script from Community Resources as I feel it'd improve the red hoops in Hot Crater Zone.
As for visibility issues, the only glaring one I could find was in Hot Crater Zone, the left path on the split where you go up then right then left feels really blind, as it usually happens then it goes up a slope. I'm not sure how easily you can fix this given how it looks visually - maybe you could make these roads specifically wider? - but I figured I'd let you know.
Keep up the good work!