I’m afraid that isn’t currently supported – but you can refine by keywords.
If you happen to control both websites then you will possibly be able to update the source event titles/descriptions to take advantage of keyword-based refinement.
Alternatively, it would be possible to filter out events not matching your custom criteria post-import via some custom development work – but I’m afraid it’s beyond the scope of provided support to walk you through that. Since we add events and event data via the WordPress API, though, you are able to take advantage of all the hooks that WordPress provides to make further alterations to the data π