This is an Idea I had, is there any way to make use of a .lst file (or something like it) to either call key frames, or set up key frames in Synfig. I see this as a way to make lip syncing work with vector mouth phonemes saved to key frames, so that you don’t have to copy key frames by hand, just inport the .lst file, and Synfig does the heavy lifting.
python script over your .lst ?