This was one heck of a story from start to finish, but I want a happier ending. A few thoughts:
1. Never go to so much effort finishing a new design until it’s proven. I did this with an F18 recently. It was unpainted for its maiden flight.
2. Balancing “nose down” is a misguided hangover from the bad old days. Find where the true balance point is with the aircraft level. Nose down just means the true balance point is forward of the pivot, not “nose heavy”.
3. The CG on a jet is rarely at 25-30% MAC. The fuselage contributes proportionately more lift than on a prop plane and its center of lift is a lot further forward than the wing’s CL, so the combined CL is much further forward.
This was a fantastic project over a long timespan. I hope you report back here someday that you successfully flew it.