Here is the full list of all 53 FateEXTELLA achievements.
Obtained all achievements.
Defeated a total of 5,000 Aggressors.
Succeeded 100% completion rate in the gallery.
Recorded all Mystic Codes in the gallery.
Cleared all stages on VERY HARD difficulty.
Prevented a Sector Trap 30 times.
Completely cleared Elizabeth Bathory's sidestory.
Cleared all Servants' sidestories.
Completely cleared Gilgamesh's sidestory.
Completely cleared Iskandar's sidestory.
Completely cleared Jeanne D'Arc's sidestory.
Raised 3 Servant's Kizuna level to 30.
Completely cleared Karna's sidestory.
Completely cleared Lü Bu's sidestory.
Completely cleared Medusa's sidestory.
Raised a Servant's Kizuna level to 30.
Completely cleared Nameless' sidestory.
Defeated a total of 1,000 Aggressors.
Completely cleared Gawain's sidestory.
Upgraded one Install Skill by +20.
Completely cleared Li Shuwen's sidestory.
Prevented a Sector Trap for the first time.
Completely cleared Cú Chulainn's sidestory.
Completely cleared Artoria Pendragon's sidestory.
Completely cleared Archimedes' sidestory.
Conquered a total of 100 sectors.
Succeeded 25% completion rate in the gallery.
Cleared the Golden Poem arc.
Recorded all Install Skills in the gallery.
Cleared Artoria Pendragon's hidden side mission, then defeated her, on four different stages.
Allied with Tamamo no Mae in the Golden Poem arc.
Revealed the true name of your Noble Phantasm 20 times.
Cleared the Dawn arc.
Defeated Nero Claudius in the Orchid Poem arc.
Performed 50 Moon Crux/Drives.
Defeated Tamamo no Mae in the Dawn arc.
Performed 200 Extella Maneuvers.
Cleared the Orchid Poem arc.
Upgraded one Install Skill by +10.
Defeated Altera in the Orchid Poem arc.
Cleared the Flame Poem arc.
Defeated Altera in the Flame Poem arc.
Switched with a vice general for the first time.
Equipped a new Mystic Code.
Equipped an Install Skill for the first ime.
Cleared Artoria Pendragon's hidden side mission, then defeated her, once.
Defeated Tamamo no Mae in the Flame Poem arc.
Performed a Moon Crux/Drive for the first time.
Obtained an EX rank in the results.
Cleared the 1st stage of the Flame Poem Arc.
Revealed the true name of your Noble Phantasm for the first time.
Performed an Extella Maneuver for the first time.