By default pyhoca-cli starts xterm without sourcing any Xresources or environment variables. This means you have at least broken filenames when they contain special characters and no Xresource options active.
To solve this you have two options.
First: Use "-t desktop" (which users probably don't want to do).
Second (which is what users probably most want):
* Set $HOME/.Xdefaults on server side, because it is the only place which is sourced when there is no X server. A symlink to global Xresources is sufficient.
* Start the app by using bash --login to source the env vars (i.e. pyhoca-cli --server <server> --kbd-layout <lang> -c "bash --login -c urxvt"