For faces, there is a topology.GetFaceByPoint function. Its usage is identical to the node and edge location functions: given a topology name, point geometry, and a tolerance, it returns a face ID:
SELECT topology.GetFaceByPoint('my_topology','SRID=4326;POINT(14.99327 50.92510)',0);
getfacebypoint
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3155
When working with a contiguous boundary dataset, it's wise to set tolerance to zero, as when a point is close to the edge, more than one face can be found within tolerance and an error will be thrown.