When running this query: https://commonsreconcile.toolforge.org/en/api?queries={%22q1%22:{%22query%22:%22e%22,%22limit%22:3},%22q0%22:{%22query%22:%22Chick_Corea_%26_Stanley_Clarke.jpg%22,%22limit%22:3}}
We currently get:

{"message":"'File:E' is not in list","status":"error"}

The filename which exists should be returned as matched, and the query which does not correspond to any existing filename on Commons should not return any candidate.