The gmic error messages in Gimp 2.10 probably caused by a left-over from Gimp 2.8 There is a dedicated version for Gimp 2.10, the old plugin does not work.
Problems with Gimp 2.8 ? How clean was the clean installation. Might need to do it again
I would use the Windows uninstaller first.
If anything left in C:\Program Files\GIMP 2\ then delete the GIMP 2 folder.
You will still have a Gimp 2.8 profile C:\Users\"yourname"\.gimp-2.8 from long ago. rename it to disable.
Install Gimp 2.8
Run it to make a new, default Gimp profile.
Hopefully an improvement.
Problems with Gimp 2.8 ? How clean was the clean installation. Might need to do it again
I would use the Windows uninstaller first.
If anything left in C:\Program Files\GIMP 2\ then delete the GIMP 2 folder.
You will still have a Gimp 2.8 profile C:\Users\"yourname"\.gimp-2.8 from long ago. rename it to disable.
Install Gimp 2.8
Run it to make a new, default Gimp profile.
Hopefully an improvement.