If for whatever reason, Stalin (and his successors) decided to keep the Transcaucasian Federation going past 1936, [1] I would think that if anything 1990-2 would be even bloodier than OTL (which was bloody enough). There would in the first place be violence between those who wanted to keep the Federation going and those who wanted to break it up, and in the second place violence (as in OTL) about the boundaries of the individual republics, pogroms against minorities
https://en.wikipedia.org/wiki/Baku_pogrom etc.
[1] It's very doubtful that they would so so, since it would be a departure from the whole structure of the USSR-- one titular nationality for each Union Republic.