Did you have you spin halyard tight? If so, ease off 6" or so. If you have a tack line, try easing that as well or instead. You may want to check your main and put on more downhaul and maybe even less mainsheet. If your boards were up and you were sailing high you may have been crabbing sideways.
I don't know about the melges, that is a big spin and in 4-6 it was helping them. Not unusually with the A Classers.
Loosen the spin luff? That allows the kite to rotate to leeward which is not what you want if you are trying to go deep. Loosen the luff if you want to go high. It is contrary to intuition, but you should tighten the luff to bring the kite further to windward to keep it in the flow for deep downwind sailing.
