Gmoccapy tool table not accepting lathe tool angles...

Indeed, tracked this to Python deprecating 'locale.format()' and replacing it with 'locale.format_string()':

github.com/LinuxCNC/linuxcnc/pull/4250/changes

Note that this issue is also present in some other places (eg the offsetpage)

Since this affects python code you could patch the files locally.
I think you would find them in:
'/usr/lib/python3/dist-packages/gladevcp/'

You will need sudo rights to change those files.

just need to search for 'locale.format_string()' and replacing each instance back with 'locale.format()'?

No, the other way around.
Click on the link in my post above and you will see the files 'calculatorwidget.py', 'offsetpage_widget.py' and 'tooledit_widget.py'. The lines marked in red need to be replaced with the lines marked in green. You will see the line number on the left.

'pncconf.py' is also affected but that is not required for running Gmoccapy.

I did find those files in lib/python3/dist-packages/gladevcp

Yes, those are the files you need to edit.