Missed Opportunities All Round
I expect Skyguide management will be found with the most responsibility as you can't expect always perfect performance from a single controller when both the conflict alert and several telephone lines are unavailable.
Subject to further CVR releases, it looks so far to me that everybody involved missed opportunities to avoid collision.
26 seconds elapsed after the initial RA before DHL advised ATC of its TCAS descent. During that time DHL must have heard ATC ordering the Russians to descend. If DHL had advised ATC sooner or asked if the other a/c had received a TCAS alert, the accident chain might have been broken.
And it would definitely have helped if the Russians had reported their Climb RA before accepting the descent instruction from ATC.
And there were 14 seconds from TA to RA where neither crew advised ATC about TCAS. That doesn't give ATC much time to sort things out, but it may clue him to let TCAS sort out the altitudes while he can help out with turns -- mind you, both crews may be more urgently occupied.
We've all had a couple weeks to pick over the TAs, RAs, FDRs and CVRs. They had less than minute and had the misfortune to zig when they should have zagged.