Hey everyone,
The tracker on certain reputation achievements seems to be a bit broken currently. This is being worked on currently and should be resolved in the near future.
The achievement will trigger if you reach the appropriate number of factions.
For example if you have the 80 Exalted Reputations, and the tracker shows some very low number (as with Ryai’s example above), if the character reaches the 90 Exalted Reputations then the achievement will be awarded.