I think that one can argue about the controller in the Ueberlingen accident, if he really has issued a clearance contrary to the TCAS RA.
No, he did not. In Ueberlingen , the controller did not issue a clearance contradictory to TCAS. He issued the clearance BEFORE the TCAS annunciated the RA.
But , unknown to him , TCAS " choose " (for various reasons too long to explain here )to make the TU154 Climb and the 757 descend.
That put the TU154 crew into conflict/doubts . The crew choose to follow ATC.
Had the RA configuration be different ( TU154 to Descend and B757 to climb, there would have been no collision, as the RA would have been in the same sense as the ATC instruction.
is there is work going on to give the controller feedback on the RAs issued by TCAS?
Yes, but on down-linking the RA message to ATC only ( Advanced studies made by Eurocontrol , called FARADS ( Feasibility RA down Link) and RADE (RA Downlink simulations in Bretigny)
Consequences of D/L RA to ATC are complex and many think ( inlc. me ) that it may induce more problems that it will solve.