So, the elytra (both in bauble form and when attached to a chestplate) all render with the graphic of a person's cape as intended (my Enderman cape became an angry enderman elytra). But rather than replace the cape on my body (like it does in vanilla), it renders both at the same time. So I have my enderman elytra when I'm wearing the colytra gear but also the vanilla cape (which does not like to behave while flying lol).

Hm, interesting. Thank you very much for submitting this issue. I have some ideas why this may be occurring, I'll see what I can do.

I have released a new update on CurseForge, version 1.0.4, that hopefully fixes this problem. Since I do not have a cape myself and I cannot test the functionality, please try it out yourself and let me know if this issue still occurs.

Good morning! I've tested it and it still seems to be rendering both the elytra and my cape. Sorry :(

Good morning!

No need for apologies. I took a look at the code again and I'm fairly sure this is due to a very small, silly mistake I made that actually made the problem worse. I have reversed my mistake and released a new new update on CurseForge, version 1.0.4.1, that hopefully fixes this problem for real this time. My apologies to trouble you so, but please try it once more and see if this problem has been alleviated.

No need to apologize. I enjoy helping the modded community in any way I can.

Also, I've tested the new version and it works BEAUTIFULLY. Thank you!

You're welcome, I'm glad to have resolved this issue for you.