You don't suppose it has anything to do with the thrust line being outboard of the center of drag, do you?
Mine has the offset engine also (see the picture of the red Sea Fury in the CEF reed speed contest thread), and I had no issue with line tension on takeoff. Looking at the thrust line of the engine, it isn't offset with left thrust. I don't see a reason for it turning into the circle just by the pics. The leadout guides look about right, but I trust you did a hang test to make sure the leadout guides are aft of the c.g.? And, there's always a left hand prop.
I'm trying to picture what's happening when that gull wing comes out of the stooge. I assume it's a sleeve type stooge? When the outboard wing is in the stooge, the whole plane is tilted away from you, right? On launch, you'd naturally have some up elevator in it. When it releases, the plane would then roll towards the center of the circle. Is it over rotating and that causing it to fly into the circle?
Mark