The real problem here is that I forgot to document a Mumble-specific variable in the OP.
There is in fact vc_[default|team1|team2]_serverversion to support Mumble serverversions correctly.
This is why an extra '?' is added to the link - it's the URL separator that should be followed by 'version=1.2.0' to correctly build a valid URL. It does not break anything if the version is ommited and just gave you problems when hacking in the version in through the channel name.
Also: You don't need to repeat server ip/port/version/anything that is the same as the default cvar. If a team-specific value can not be found (is empty) the default value will be used instead.
I have updated everything, including support for a server password in mumble, in the OP. I don't know how that version and password stuff slipped through so sorry for that. Also RaidCall support is now in the OP, I figured it works correctly since no one came back and complained about it.
Code:
* 1.1.015
- Added server password support for Mumble
- Added missing docs regarding the serverversion cvar for mumble
- Added server name support for Mumble