it would be easier to just use Kata
https://forums.online-go.com/t/server-comparison-ranks/50428/7
with more data, like 100 games from each OGS rank it would be possible to properly measure angle of border between ranks in (number of mistakes)X(size of mistakes) space
then we could plot perpendicular line to that border
make projection of these dots on this perpendicular line
average coordinates of these dots to compress them into 1 dot each
Then we would get unique dot for EACH ogs rank, they wouldn’t be too close to each other
Then we could do all this again for each rank of each other server and paint resulted dots on lines that are parallel to OGS line
Then we would get picture that perfectly compares all servers