I know well the issue(s). I don't run a WinBox currently.
as already mentioned in an earlier mail, the culprit is not with the script itself, though with some leftovers in the pre-compiled zip files used by g.extension in winGRASS, see
https://lists.osgeo.org/pipermail/grass-user/2021-March/082299.html
downloading the zipped addon, which is used by g.extension in windows, from here:
https://wingrass.fsv.cvut.cz/grass78/x86_64/addons/latest/in the subfolder i.fusion.hpf\etc\i.fusion.hpf, there is a subfolder __pycache__
i.fusion.hpf\etc\i.fusion.hpf\__pycache__>ls
constants.cpython-37.pyc
high_pass_filter.cpython-37.pycthe compiled python bytecode shouldn't be there in the zip file.
@Martin: anything to change on the compilation server?
that's the reason of g.extension failing
downloading the zip-file (see link above) and copying the files into the corresponding folders in
C:\Users\YourUserName\AppData\Roaming\GRASS7\addons\
should help.
kind regards
Helli