Gave the editor a try again with the new fixes, and found a few things:
* Sidewalk-road curved corner piece appears slightly lower in the editor than it will be when playing the level.
* Sidewalk appears slightly higher in the editor than it will be when playing the level. (Tried this out by placing a decorative on sidewalk and see if a gap appeared under it when playing.)
* Found a way to consistently cause zebra crossing road to duplicate when it shouldn't:
1. Try to duplicate (ctrl + D) an existing zebra crossing road piece. (But it will not duplicate)
2. In the TAB drawer menu, click the zebra crossing to place another one.
3. Deselect the newly placed road piece.
4. Select it again and move it a bit. A duplicate should have appeared.