This is actually not a bug, but a poorly-worded achievement description. Originally when the craglorn trials were VR12/VR14 completing them within 33 minutes was enough to earn the time trial achievement because the only way to complete them was as a timed trial. Now that they have been updated to cp160 the only way to earn the time trial achievement remains by completing the timed (i.e. veteran version) trial, even though the achievement description does not specify that it must be completed in veteran mode.
It would be better for the achievement description to be updated in a similar way as the Maw of Lorkhaj time trial achievement: "Complete Veteran (insert Craglorn trial name here) while it is scaled to Champion 160" so as not to be misleading.