Good news....My 2 day old P3SE and 2 day old iPad Mini 4 went for a few basic WP missions on Litchi today to test it out... Everything seems to work with no glitches.. no lost signals... nothing.
It flew each mission perfectly... each mission, I added a bit more to do for the missions... POI's, FOCUS, Rotation... start/stop recording.. etc. it all worked.
I am new so need to keep trying different aspects of the app to 'find' the bugs/glitches ( if any I can find ). I did try FPV for a quick minute... but didnt go through everything... since I dont know everything in the app yet.
I would be doing some controlled tests on a few of the critical features, especially confirming RTH initiates on follow, focus and track modes. There was an earlier issue where RTH would initiate with the standard/4K in signal loss flying with these litchi modes. You could test by turning off your controller with the AC in sight.
While autonomous flight modes are great I would be spending time also on your manual flight skills, make sure you can get the AC home if something goes pear shaped with litchi.