A suggestion I have is to add an copy and paste button for the three positions, and the three rotations separately, so that it is easier to transfer the numbers to either the same part or a similar part in a later or earlier frame while correcting for inconsistencies.

Without this feature, all the positions have to be tweaked manually over each frame they add, and that time adds up.

A second suggestion would be a downloadable UV map. make the drawing/texturing portion easier.

How this would work is that someone pre-arranges all the body parts' UVs onto the map like before, but there's a button to check ALL the UVs' positioning, and when all the UVs are put in the right place by the player, there should be a tab to "Print Total UV Map" with a warning to arrange all UVs properly.

This UV map will be a .png file, to which you can overlay your skin to draw within in a different program.

Without this feature, You would have to manually edit each UV's position and texture on a one to one basis to pace yourself and not get lost on where each UV is, and that time adds up.