Thanks for reporting the crash. I got that fixed just now and should be available in next week’s build.
Remember you are opening the older python 2 files in the new editor that opens in Python 3 by default and there are differences between the two that might need adjustments to the scripts.
To use Python 2 (IronPython) either add #! python 2 to the top of your script, or renamed the file extension from .py to .py2
I seem to be running the Add layer block.py with no issues here in Python 3.
I know about the missing LayerTable.Find problem and will get that fixed:
RH-76154 rs. Parentlayer fails at LayertTable.Find in Scripteditor
Would you mind sending me the scripts that are crashing?