Just a two center here. Totally minor points.
The status message after a save/export/etc can block the controls underneath, must pause until message fades before next click.
IMHO it is bad practice to use timed status messages. Too fast for some, too slow for others, just right for nobody.
The messages themselves are grey on white sorta thing, a bit challenging for eyes past their prime. A long path gets bumped off the background, it's not readable at any age.
There's a bar along the bottom. A usual place for status messages.
Fantastic tool. Looking forward to it. Hurry Up !!!