A buddy of mine and I were working on the achievement together, using this https://wiki.guildwars2.com/wiki/Skyscale_Rift and I noticed that the number of rifts in each region doesn't match the number stated in the achievement. Shiverpeaks Mountains has 13 but the achievements showed that there is 14. Also, one of the two rifts in Metrica appear to be bugged, it doesn't give credit for completion. Kryta and Maguuma Waste were the only 2 regions that seemed to have the correct number of rifts. Either there are new rifts added into the game or the achievements is showing the incorrect number.