Hi ,
As you noticed, renaming classes is generally not a good idea. It can potentially create a large number of additional problems, depending on how widely you are using that class in your project. If at all possible, try to avoid renaming classes.
I was able to reproduce the issue that you described, and it does look like something we could potentially handle better. I also ran the same test using our latest internal build and the Editor no longer crashes when you right-click on the Blueprint in question. I did see a crash when selecting one of the menu options though, and I have submitted a report about that to our development team for further investigation (TTP# 347299).
However, the only way to reparent a Blueprint at the moment is to actually open the Blueprint, which I was still unable to do in our internal build. I sent in a feature request as well to find out if it would be possible to allow for Blueprints to be reparented without requiring that they be opened (TTP# 347300).
Thank you for bringing this to our attention. You will see some improvements in this area in future versions of the Engine.