Instead of fill_rainbow treating my project with how the LEDs are wired how can I get it to use one of the many maps that I’ve created?
I don’t think FastLED supports this, bit if you look at the fill_rainbow implementation at https://github.com/FastLED/FastLED/blob/dbd2d8b8ca037f9d2d5e743785abac28b125c947/colorutils.cpp, you’ll see it’s quite a simple thing to implement.
I’d take a copy of that function and paste it in your code with a different name, and replace the i in pFirstLed[i] with the index you want.
No problem at all! You should share some photos or video of your project at some point