Looks to be your first time mapping, yeah? It's rare for first-timers to be using Paraglide sections and apparently building around gameplay mods like tricks. I respect it!
Before we've even begun, however, I'd like to begin with a nitpick. You've already stated that the maps are separated individually and will rectify that in the future so I won't talk about that. What I DO want to talk about is the fact that the file sizes are pretty big for single maps and how it stems from large, non-looped music files. I strongly recommend learning how to loop your music so that it cuts down on file size for those downloading from servers as well as keeping the music going on races that take longer than the music file goes on for. These links here are pretty helpful:
https://wiki.srb2.org/wiki/Sound_and_music_tutorial#Looping_(optional)
https://mb.srb2.org/addons/how-to-properly-loop-your-music.3049/
Let's get into the maps:
N64 Choco Mountain: You've got the general layout down pretty well. It's just that the textures aren't very varied like in the original game. It also feels like driving down giant hallways instead of a mountain. The mountain face area suffers from Z-fighting (flickering, noisy rasterization of two polygons) issues in OpenGL and could cause issues for those with eye problems. The paraglider section is pretty strange. The sounds for the paraglider are missing and instead use the backup sounds, and it's a huge valley of nothing but water. The rockslide area also doesn't steadily rise up in elevation like in the game which turns it into a very strong shortcut that's easy to take for any placement. And the final section is just two giant Vs rather than 3 humps. I can also see outside of the track due to sectors that aren't closed all the way.
CTR Crash Cove: A LOT of items here but they're all not very far from one another so the time to use them is pretty short. The first ramp is extremely slow. I know it's there in the original game but kart's physics are different than CTR's so you gotta take into consideration how coming and going off a ramp feels in this game. Speaking of ramps, the shortcut right after blends into the ground due to it using the same texture and doesn't require a shoe to use meaning even 1st can take advantage of it. The drop off of that shortcut is also pretty blind and leaves a high chance of bonking off the sign and into the water. The ship is also now just scenery instead of being a part of the track. If there's no real reason to go over there, you should just block it off so people don't go there accidentally and end up wasting time.
CNK Meteor Gorge: This track has a lot of non-smooth slopes that end up obscuring the track as you drive but most importantly, several background elements of the track, like the area around the first item set, are NOT blocked off and doesn't even have step-up to get out of there which makes it very easy to softlock someone in there, forcing them to use the respawn command. These problems should DEFINITELY be fixed as soon as possible.
Not bad for your first couple of maps.
