Just to clarify those people who are at the top of leaderboards with some crazy scores/times are not cheaters (except for the Anulpha pass zones where people used the old exploit, they were cheating). Its just the leaderboards are glitched at the moment and nobody has been around to fix them.

The extent to which this will affect your ranking will vary vastly as some are worse off than others, for example I'll use the Syncopia zone leaderboard. All scores after 75th place are glitched so in this case you would take your current rank and minus 74 (further example my current rank for Syncopia zone is 111th - 74 = 37th place true rank).

Your best bet is to manually scroll through each leaderboard, find the best legitimate score/time, count the glitched ones before it up to rank 1 and then subtract that from yours to find your true rank.