The complete list of managed wikis is not available for now in MediaWikiFarm. It should be created such a list by iterating over defined wikis in the 'variables' files and in the 'versions' file, farm by farm.
Although the basic thing is just iterating, it would be better to add, for each wiki, its complete ID, its suffix, and its URL. To achieve this, the URL regex should be “reversed”, I guess it is not too much complicated but some care must be taken.
A direct use (a specific task can be created for this) will be to update all wikis in one command (update or possibly another maintenance script, e.g. runJobs would be useful also). A second use (also a specific task to be created) will be the basis to create proper statistics about the farm (e.g. how much wikis, how much different MW versions, how much a config parameter is used, how much different values, etc.).