This plugin can export and import TVPaint's layered animation format. The format contains a CSV (comma separated values) textfile (filename.csv) and a directory (filename.frames) with png images of the keyframes. TVPaint itself can only export this format, but I'm working on an importer script for TVPaint too.

Remarks: Both the import and export part works good for me. This format is incapable to contain grouped or masked layers. I don't know yet what to put in the test part of the plugin. There are still minor glitches, like the behaviour of the main window statusbar during importing.

Create an animation, export it with this format, then try to import it back. If you have access to a full version of TVPaint, you can export something from it and load it into Krita.