Welcome and congrats on your first sheets!! They look very nice so far, and you've done a great job notating those tricky rhythms especially. I just have a few comments on the rhythms in Cheese Land:
-You almost always leave beat 3 visible, which is exactly what you want in 4/4 so good job! I did see a couple of spots where you might have missed this however (like measure 44 in Cheese Land) so it wouldn't hurt to double check.
-In the section from measures 9 -14, on beat 4 you sometimes notate the rhythm as two eight notes and other times as two 16ths separated by 16th rests. I think it would be better to keep this consistent as eighth notes, and if you do think there's a length difference (I didn't listen closely enough to tell) to use staccatos on the eighth notes rather than switching to 16th notes.
And some Cheese Land comments not related to rhythms:
-I would switch the left hand to bass clef since that's what piano players are accustomed to reading, and there's really no reason to use a 15vb treble clef when a bass clef exists. If it goes too low in bass class, just write it an octave up and indicate "8vb" in the score--no need to change clefs!
-There are a couple of spots where the second voice in the right hand has stems facing up instead of down, which is causing them to overlap the top voice in places. Knowing Musescore there's two possibilities here: either the notes were accidentally entered into voice 3, in which case you just have to switch them to voice 2; or you accidentally flipped the stems when entering the notes in which case you just have to select the notes you want to change and press "x" on the keyboard and they should flip right back. It's an easy fix but it will clean it up nicely

I didn't look over Shy Guy Beach in too much detail but I hope that was helpful! The sheets were quite clean and easy to read in most parts and those were some pretty minor complaints, but fixing them up will go a long way!
I'm glad to see some more Mario Kart sheets in the works, those games have always had great music!