Community template install impossible

You have added sudo to the qvm-run command.
This wont work because sudo will not operate through redirection(>)
My guess is that you are trying to copy the template to somewhere owned
by root. The sudo command runs the qvm-run but the output write is
performed by user.
There are ways around this:
sudo su - to get a proper root shell
Or qvm-run -p QUBE 'cat path_to_template' | sudo tee template name > /dev/null

I would just copy the template to somewhere owned by user.

I cant replicate your error in setting up the repository.
What version of Qubes are you testing on?

I never presume to speak for the Qubes team.
When I comment in the Forum I speak for myself.