I'm of no help of than I feel your pain.  I had dozens of curved terrace lines and field borders I've saved over the years with an AL ontrac3 and 6500 with the Terrastar correction.  New planting tractors came with a paradyme/RTK sytsem in it.  None of my curved lines that I've been using for years seem to line up with the paradyme system.  Strait lines seem perfect so far.  Not sure if it's even worth saving the lines this year as I think I'm going to swap out the system for a steer command and 7500 next year.  Just not sure if I should go back to terrastar continue with RTK.  I've always been happy with the year to year repeatability from terrastar even thought they told me it wouldn't do that.  Maybe I just now am finding that out?