thanks for the report.
I had in mind to add some things that you said here.
The program try to touch only the neccesary lines of the code leaving the rest of the lines unaltered so you shouldn't lose anything, comments, scripts or anywere.
The standalone images preview works well, but the level preview is not working. It is just the bottón blank pannel that you can see in your video.
it should have this aspect.