Bool fields apparently have to be int in the database to get them to work... changed them.

The Indexfieldconfig now contains the correct fields which are necessary to run the search.
The fields now can be configured via the client. Those infos are now used to dynamically load the configured fields an their values which are then internally used to run the prefilter as well as the real duplicate search.
NEXT UP => Configuring of the result fields. There's light at the end of the tunnel.