Well, the updates in FFRK JP went like this:
Game Release:
spoiler (click to show/hide)
tutorial
[FF7 / FF10] (Reactor No. 1 / Zanarkand)
[FF4 ①] (Beginning to Baron Castle 2nd time)
[FF5] (Wind Temple to North Mountain)
[FF6 ①] (Narshe to South Figaro Cave 2nd time)
Update 1 (Oct) - FF1 and FF2 were added
spoiler (click to show/hide)
[FF6 ②] (Phantom Train to Ultros battle)
[FF6 ③] (Airship Entry to Magic Continent to Escape from Magic Continent)
[FF1] (Chaos Temple to Astos (boss)
[FF2] (Semitt Falls to Snow Cavern)
[FF4 ②] (Lodestone Cavern/Metallic Cave to Summon Cave battles - it's really really long)
[FF6 ④] (Solitary Island to Daryl's Grave)
Update 2 (Nov) - this is when FF8, FF3, and FF13 were added
spoiler (click to show/hide)
[FF8] (Fire Cavern to Tomb of the Unknown King)
[FF13] (Hanging Edge to Vile Peaks (Odin Battle))
[FF1 ②] (Earth Cave to Gulug Volcano)
[FF2 ②] (Dreadnaught)
[FF3] (Altar Cave to Nepto Shrine)
[FF10 ②] (Kilika Forest to Mi'ihen Highroad)
[FF5 ②] (Walse Castle to Ancient Library)
Update 3 (Dec) - FF9 and FF12 were added
spoiler (click to show/hide)
[FF13 ②] (Gapra Whitewood to Sunleth Waterscape)
[FF8 ②] (D-District Prison to Fisherman's Horizon)
[FF9] (Prima Vista to Burmecia)
[FF12] (Nalbina Dungeons to Lhusu Mines)
[FF3 ②] (Tower of Owen to Goldor Manor)
[FF7 ②] (Gaia Highway to Shinra Cargo Ship)
[FF13 ③] (Palumpolum)
Update 4 (Jan)
spoiler (click to show/hide)
[FF7 ③] (Corel Prison to Gi Cave)
[FF1 ③] (Ice Cavern to Flying Fortress)
[FF2 ③] (Deist Cavern to the Leviathan)
[FF7 ④] (Nibelheim to Temple of the Ancients)
[FF6 ⑤] (Death Gaze to Cave on the Veldt)
Update 5 (Feb)
spoiler (click to show/hide)
[FF10 ③] (Mushroom Rock Road to Macalania Lake)
[FF1 ④] (Chaos Temple Pt 1 to Pt2)
[FF4 ③] (Sealed Cave to Giant of Babil)
Update 6 (March)
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[FF2 ④] (Mysidia Tower)
[FF9 ②] (South Gate to Cleyra)
[FF5 ③] (Desert of Shifting Sands to the Catapult)
[FF9 ③] (Alexandria Castle)
update 7 (march)
spoiler (click to show/hide)
[FF3 ③] (Dragon Tower to Saronia Catacombs)
[FF2 ⑤] (The Cyclone to Jade Passage)
[FF13 ④] (Nautilus Park)
[FF5 ④] (Tycoon Meteorite to Ronka Ruins)
Update 8 (April)
spoiler (click to show/hide)
[FF10 ④] (Sanubia Desert to Via Purifico Pt 1)
[FF13 ⑤] (Palamecia)
[FF5 ⑤] (Walse Meteorite to Exdeath's Castle)
The JP version is getting an update later this month for more FF8, FF10, and FF12 stuff, and then FF5/FF12 in May.
I think they might be changing up some release and event schedules for the western version, though. They already did by switching the FF7 and FF4 events around (since FF4 came first and then FF7 afterwards in the JP version). They already changed the FF4 story segments and backgrounds from the sprites in the JP version to the DS/iOS versions. So yeah, they are trying to make it more accessible for western audiences being more familiar with certain games over others.
As for me, these FF5 updates are way too far apart.