It all works!
The images match to the events faultlessly. I’m using a remote intervalometer/trigger timer for the Canon5D Mk IV at 1 [second] intervals.
The Klau Software is great.
The Pixhawk is a cute thing, musical tones and flashing lights. Mission Planner is a good too.
My camera calibration comes out better too. Pix4D says 0.01% relative difference between initial and optimized internal camera parameters.