Michael,
I have only had one fully fanned junksail, and on this the leech leant over forward, as on Colvin’s sails. I had a single sheet on it, and as a result, the sail, boom and battens caught the sheet every time I tacked, until I learned to throw the sheet bundle over when coming about. Gybing was even worse. As a result of this experience; I have done my best to make the sheeted part of the leech vertical - or even leaning a bit aft. - on every sail design after that (1992).
If your present sails are old and tired, could I suggest you make a new set to a new design?
Arne