Great pack! All three maps gave me really good impressions, they all look great, and aside from minor gameplay gripes, they were very enjoyable to race on.
Boulderstone Alpines Zone K is, personally, my favourite one. No real flaws, incredibly readable even without the use of signage. Excellent work.
I'd encourage you to use fricfix for Boulderstone Alpines Zone K's low-friction ramp (10 seconds-ish into the lap), as this makes it so using speed items (Sneakers, Hyudoro, Invincibility) don't eat the increased speed from the ramp, you can find it here:
https://mb.srb2.org/addons/jugadors-map-script-collection-context-tags-fricfix-kmp-respawns-handler.3407/
It's by no means required but very welcome and appreciated by speed junkies everywhere.
Chartreuse Woods Zone also looks amazing, you made the forest theme look just right, and the lighting on the hollowed-out trees and shadows in general make the whole place look believable - lighting work is definitely underlooked in Kart levels and I think you went a step beyond here.
My small gripe is right at the start of the race, where the slight incline obscures the first turn and the chevron you used doesn't make that clear. You should definitely change the ground in such a way that it makes this turn visible. Aside from this, it's all perfectly readable, so congrats!
You cited Digital Botany Zone had visiblity issues, so I was surprised that, aside from that setpiece with the yellow and red spring sector panels right at the end, I didn't really had any visibility problems at all. I do agree that the lack of shortcuts makes it a tiny bit painful, but it's by no means unplayable, and I do think the layout in general has a solid foundation for shortcuts. If you're looking for inspiration, I thought this layout was very similar to Udgey's House of the Undying from Draft Tracks, so maybe you could look for inspiration for shortcuts there as well:
https://mb.srb2.org/addons/draft-tracks-v3-kodachromatic-chills.3410/
If reviews allowed a 10 star rating, I'd give it a 9, but since it's not the case, 5 stars for you, keep up the good work!