Not completely. But it seems to be better now.
I tested with the crashes.capx on my very low-end laptop, to see what is the difference between r276 and r265.
With r276, i had about 500 large sprites on layout,then opened editor and duplicated few frames, then deleted them, then exited the editor and saved,and while it was saving, i moved around with ctrl+mouse wheel, it crashed every time.
With r265, C2 was unresponding for a moment, but always recovers and never crashes.
With my high-end desktop PC (r276), it crashes, but not as often as it used to.
Yesterday i had 2 crashes, today 1. On both days i worked around 6 hours, using the editor occassionally.
Earlier today i tried to make it crash using my project, which is 22mb in size and has a lot of sprites, between 600-800 per layout, and i did manage to make it crash by quickly deleting 40 frames from one sprite, then exiting the editor, saving, and moving around with ctrl+mouse wheel.
If you have a low or mid end PC or laptop, you can make C2 more easily crash, and with high-end PCs it might take a while before it crashes, but eventually it will.
Before r276 it crashed in 1 to 10 minutes after using the editor.
Now it seems that it may take a very long time for the crash to occur.
Do not try to make it crash with very small project + high-end CPU, it most likely won't work, since there is not enough stress on the CPU with small project. Use low-end PC or laptop if you have one. And have a big project with a lot of sprites and frames.
Try also having a lot of objects on layout, so that saving takes a bit of time, and is not instant.
The reason why with some people it crashes instantly, and with others takes a while, is the differences in peoples CPUs!
If you have not altered the editors code since autumn 2018, it must be the third-party plugin the editor uses.
Talk with the creators of the plugin, maybe they are not aware of the problem.