Ok prior owner here. So yep I'm the problem (I get it).
Mast should be raked, and it looks like it is, hard to tell with rotated pictures though. If you (in the water) hang a hammer from the main halyard in calm water, the total measured rake (at the boom level) should be about 3-5 inches away from the gooseneck.
What I wanna know is why you put 2 backstays on. The flicker cannot do its job if the original steel backstay is in place (the roach of the main catches on it). The purpose of the flicker and the amsteel blue 3/16 is so that when you release the cascaded backstay, it allows the light line to rise clear of the roach, with the steel backstay on there, it'll always be in the way, and wear the edge of the mainsail. No need to worry about the mast coming down the mainsail is up for this adventure and also the mast would stay up anyway as this is a highly swept spreader rig, and the mainsheet and mainsail would prevent it. Remove the steel backstay (unless I am seeing an illusion in the pictures).
For the record I am NO expert on the boat, but the guys at www.s279.org
The objective is for you to be able to ease the backstay (downwind) and allow the top of the mast to come up a bit, which requires the uppers to be ever so slightly lower in tension then the lowers. Given this you are flexing the top section of mast to create "bend" or release "bend" in that telephone pole of a mast (yeah it doesn't bend much), but it does make a huge difference in forestay sag. In the "really" light, like under 6 knots wind, you ease that backstay a lot to power up, and slowly add backstay as you get moving. But each tack you must ease the backstay almost completely so that fuller roached mainsail can clear the backstay without getting hung up. In over say 8 knots true, the mainsail won't catch and screw up your tacks, and its more important to keep forestay sag at a minimum to reduce heel.
So the procedure (for you and crew) is to call "ready about" on "aye" you ease backstay, start your tack, headsail flops to backwind, release genoa sheet, complete tack (turn)... overshoot close hauled to close reach, leave backstay off until you are 7/8 prior speed or so working your way back to close haul, and slowly adding backstay tension. In light air that tension shouldn't be much. You'll find in anything over 10 knots backstay has to be on through the tack, and over 15 knots on a lot and you'll start to see serious scallops in the mainsail halyard (halyard tension will likely need reset).
That boat will eat winds up to about 35 knots. If you drop down to the 105% you can sail with a reef and very little tiller. I found that boat to be extremely forgiving in nearly all points of sail, but it likes wind the most. Almost never sailed that thing with a reef, we just don't get enough wind on our lake for it, maybe a half dozen times or so, when winds were peaking over 25.