Hi, I'm not sure about what I'm going to say so take it with care:
About the permission error I think the build directories are write protected by default it Guix, please someone correct me if I'm wrong. I'd say you can change the permissions of the folder with the chmod util, you can see many packages do it. Just call it like: (chmod filename mode) Being `mode` something like #o664 for an equivalent `chmod 664 filename` bash call. So I guess you need an extra build phase to correct the permissions on the folder so the script can write to it. Maybe that will fix both errors, but make sure also that you have the dependencies for ElementTree, just in case. I hope this helps... Best, Ekaitz
