I never corrected any garbage matte lines, but if you mean matte boxes, then I "corrected" those through colour-timing only and did so because under ideal conditions they wouldn't have been visible in cinemas in 1977 - so again, just trying to preserve/restore the original movie-going experience.

I did make some choices where to leave the SE footage but that was in 99% of cases with the invisible fixes where you probably couldn't see the difference, unless you saw it side by side, frame by frame. Which of course does make it possibly less than 90% truly accurate to the actual film but takes it pretty damn close to 100% accuracy to the original experience.