The ARR Extremes have the additional issue of staying in your quest log till you manage to get through them. Newer Extremes see their quests completed without having to actually do them. The ARR ones give no hint that the difficulty is not in line with the previous version of the fight now just at higher level and for unlocking you are on a convenient "here let me help you queue" spot. Those trials are in the normal difficulty tab alongside other "hard" content like the level 50 versions of the ARR dungeons.