Using term "Server" on the Login screen is a bit misleading as the server itself may have a name which is different from xmpp server's domain. So it would be more logical to use "Domain" there. As Server is used prominently in Spark and all the translations, it would be good to change as many places as possible (translation also).
Then user guide needs an update of a login window screenshot. But as many users will still be on older versions, we should just add a Notice, that this field is called Domain in the newer versions.