It should hide taxonomy values that have no posts in combination on other selected taxonomy. Even better would be to leave them open in hierarchy but to have option to disable clicking on values with zero posts in current combination of selected other tax.
(Query multiple taxonomies work similar, but the problem is that it hides taxonomy values when user select one. It should leave them open so user can walk thru categories and filter posts on the way and not going back all the time)
Counter should also show number of posts in current combination of selected taxonomies, not all... but even if you leave it like this is better then nothing :)
1.Selecting tax A (auto confirm dropdown)
2.Selecting tax B / list all available categories-hide empty ones or disable clicking on empty ones in current combination (auto confirm on selection)
I think this walking thru filter would be useful for many users.
great plugin anyway!