Hey @Roni,
First off, I do want to note that we are fairly limited in how much we can support custom development questions like this — that said, I’d be happy to help as best I can to at least point you in the right direction!
As of 4.0 Filter Bar does support PRO’s additional fields. That might give you some flexibility as far as adding filters.
At the same time, I do not believe that it would all that easy to add other filters without modifying the plugin’s core files — something I wouldn’t suggest doing, or at least without ensuring to document those changes before updating the plugin when future releases come out.
If you were to create your own filters, they would either need yo hook into the plugin’s tribe_events_filter_view_do_display_filters() action or you would need to add them to the plugin’s template directly.
Sorry I don’t have a concrete answer for you, but does this at least help you get started? Please let me know.
Cheers!
Geoff