By no means exhaustive, but I would recommend giving your levels of a more through review on directioning sometime or watch people sightread them.
Dawnstar Garden
This is kind of a recurring theme with a few of your maps - there's simply too much going on. The player's eyes are drawn in several directions and there's a ton of bright colors. There's an untripwired shortcut, a pillar with a trapping corner that you can get stuck in. The player will not likely see the Ark Arrow for the shortcut and will have to do some really tough sightreading.
Indierock Rally
I'm aware you have a custom directioning in place here (yellow transparent arrows), but in some instances it is not used at all when it needs directioning (like here). In some instances, your map design itself doesn't do enough to alert the player of what's up.
This section actually does have a better sense of guiding the player because of the bright wall. Indierock is a very dark level with purple floors on dark blue/purple walls, and things kind of blend in too much. Aim to rely more on things like this.
Ripple Metrocity
This is the only instance of you not using an Ark Arrow here. I think it blends in too much with the color palette of this level and should be in front, not behind the beams.
This Ark Arrow is not only completely invisible from finishing the circuit until you drop down, presumably at high speed, but blends in with the rest of the very green color palette. Yellow is used for right angle and sharp turns, but you might want to use it here and move the placement/make it bigger so it's more apparent to the player.
Jade Garden
You use a lot of this style of sudden u-turn in your maps. It is not conveyed here at all, not even by the Ark Arrows and is poor. This will always trip up new players in a way that I think is unsatisfying.
Okashi Overpass
Needs an Ark Arrow. There are rings on the left, but the actual turn is to the right.
Sakura Serenity
This is not conveyed well as being a wall transfer. Good wall transfers lead the player into their turn (see Haunted Ship in basegame) instead of coming from a perpendicular angle.
When you are coming at this above 100% speed, a player who isn't well aware of the timing will almost always mess this up. Your solution is to simply give the player a freebie if they do nothing, but you DO tell them to fastfall with the Ark Arrow. It is too strict IMO.
Moonlit Sentinel 2
Directioning needs to be at the purple dash ring and not after it. I think if you add that it'll be fine.
Sunrise Grove
Kinda dig this level a fair bit, actually. Could maybe be 4 laps. But this left turn should have some kind of directioning, and the right one should have the Arrow be in the center of the player's view.
Aqua Hazard
This is not telegraphed enough and should use a yellow sharp turn Ark Arrow.
Sunset Archipelago
Ark Arrow should more directly face the player going in the direction of the road.
There's a bit much going on here and it very much hides the Ark Arrow at the very end of the circuit. Reduce the amount of texture detailing or find a way to point the player towards the Arrow (and use a sharp turn yellow one).
Myouka Shelter (isn't this just Foliage Furnace?!)
This vid feels like it explains a lot of what I find difficult to parse about this level:
- You are using the same texture on the floor and walls (green and blue, red and purple happens earlier)
- Your floor and wall textures are using the exact same colors
- Multiple, clashing directioning items
- Ending should use Rings or some leading to get the player to the next section
- Highly dense amount of detail on both floor and walls makes it hard to read
The lack of directioning here plus the spikes is too mean-spirited.