Only german, yes. They explain on https://wiki.uberspace.de/philosophy:englisch why (in german): it boils down to too much work, not being sure of being able to adequately support in english, having servers only in germany and fearing legal implications of having an english offering.

With google translate and maybe a bit of help from a german speaking friend (and a bank that supports wiring money to a german account without problems) that is probably still manageable, but not ideal.