The plane was 98% trimmed in 6 flights.
The engine might take the rest of the season to get right...
Suggestion:
Join the flaps with both sitting flat on the flat building surface.
Get them dead flat and glue together with the horn.
Install hinges in flaps.
Install flaps to wing.
Never touch the flaps again. All roll trim is to be done with the wing, either by slight warps of the outboard wing or trim tabs. Tweaking the flaps does nothing at all for roll trim on this design.
It is a little bit harder installing the flaps the way I said, but it the only way to ensure they are dead flat to one another.