When I hand painted each cell in Callipeg I found that the paint would crawl and flicker from frame to frame.In this scene she simply throws her head back and opens her mouth more to belt out the final note. The paint flickering was distracting. All of my illustrations were done in Procreate which has much better brushes.
I decided ti import all the animation drawings I had done into Procreate. I then took this first frame and used it throughout the scene. Rather than repaint the flesh each time, I simply stretched and morphed this existing painting. The result was exactly what was needed.
Exporting frames with transparency is still something I am trying to work out. I exported the scene back to Callipeg to get the timing right but a white background exported with each frame. I had to erase all the white since Callipeg does not have a magic wand selection tool like Photoshop. That is a painful and unnecessary step. The clip I imported into the final edit had some white flickering from small spots I had misses with the eraser.
Now I am considering cleaning up the shot in Procreate and exporting with transparency directly. This could be a good workflow, but I am still working out the kinks.