It was very easy to do! This is what I did:
Draw the frames in Animation Paper. Export the frames as OCA using the png format. This creates a map with the frames as png images numbered in the correct way. In Tahoma2D just drag the first image (1_00000.png) to the canvas and choose import. This will create a new layer in Tahoma2D with all the frames. In Tahoma2D you can edit the drawings when needed.
I tried the same thing in Opentoonz, but there seems to be a scaling issue.
In Tahoma, when you create a new smart raster level just below the imported layer, you can use the fill tool to colour the drawings. And when you are done you can even change the color in all frames at once by adjusting the color in one f the frames. I hope Animation Paper will get a similar function!
The reason I did the drawing in Animation Paper is the the intuitive interface and the excellent drawing tool! I love working in Animation Paper.