In article , Knecht
writes:

Relativity is safe for now and probably will remain so for quite some
time, that is, as long as we let observations resolve scientific
issues.

As the moderator's note in another post in this thread pointed out,
relativity would still be safe even without the new issues you mention.
The two things (CMB as a "universal reference frame" and how this jibes
with relativity on the one hand and the large-scale flows etc on the
other) have nothing to do with each other.