Yeah, that's good to know. I stumbled across something less interesting when I first started clearing out the expert version of Red Spider Lily's Aqua Shadow stage: rainbow healing tiles like the ones granted by Choco Cosmos (Easter) will change their colors if they land on the red, blue, and/or purple tile in that stage.

Here's what the stage looks like with no healing tiles:
[Chat Chit] DMM FKG-aqua-licorice.jpg
Here's what it looks like when the purple and blue tiles get choco-fied, with a yellow tile also choco-fied for comparison:
[Chat Chit] DMM FKG-choco-licorice.jpg