One thing I noticed about scroll zones:
Depending on where the camera is the current area, when you switch to another area, the camera will move horizontally (assuming they're connected horizontally) then it can find that it's showing something outside the zone (e.g. above the zone) and will warp to be within the zone again.
I hope I worded that clearly enough, lol. Maybe there could be a way to scroll more smoothly? For example, in Super Metroid (which uses a little different scrolling for within the same room anyway to keep proper focus), the camera would move vertically to align itself with the next zone, then scroll horizontally. As long as it isn't warping that would be good.