The AdvancedSearch is very useful, but it does not work on Miraheze because it depends on CirrusSearch, something not available for us currently.
According to Reception123, there have been talks about implementing CirrusSearch in some way in the future, but this is not a priority and will take a very long time to decide. In the meanwhile, the panel "Advanced Search" on the search interface provided by the extension is basically useless in this situation and could be removed, if possible.
While technically speaking, the extension is "useless" in this state, I don't know if it should be removed completely (for now), because it does not provide literally any different functionality without CirrusSearch.