Time in XIV is measured no less than three different ways, and not one is compatible with any other. Each time we try to explain it, it gets a little more precise, and though it’s confusing at first, the dev. decisions are pretty logical.
The In-Game Clock
One year in clock-time is 18 days and 16 hours earth time. Forget “What year is it?”, we should all be dead by now. Think of this as time relative to game mechanics. It keeps the world feeling alive, and semi-accurately reflects, say, how it takes “all day” to clear out a dungeon or “a hard day’s work” to gather up some timber or “hours” of travel time.
The Lore-Time Bubble (aka The Simpsons Bubble)
Lore time passes, but it does not move. Even if you can prove that 5,000 days passed, the year does not change. It is, and will always be, 5 Seventh Umbral Era [into/also known as] 1 Seventh Astral Era.
The lore-time bubble expands ever outward, infinitely approaching but never actually reaching a new year. It’s up to you how you wish to interpret that for your character. Perhaps, by the time the servers go dark, it’s been one hells of a year for you. Perhaps your character “actually” spent decades walking around. It just can’t be enforced upon anyone else. This is the canon time, and it keeps things working smoothly internally (less math, less mistakes, less time spent changing “It’s been X years.” every patch) and for players (who have a consistent understanding).
Real-World Time (aka Meta Time / aka Player Time)
Holidays take place within their own unique bubbles that are within but without Eorzean “hard-canon”. Everything that happened in Eorzea happened within the sub-bubble, but not everything that happens within the sub-bubble has to happen in Eorzea.
Think Hildiband (which I joke as having taken place in The Manderville Bubble); Eorzean history is still true within the bubble, but could Hildibrand survive point-blank explosions to the face and multistory falls with nothing but a silly change of expression in a world where people are regularly devoured by raptors while picking pumpkins? Probably not. (Not to mention the primal Enkidu, who is technically a primal but not at all how primals work.) But that’s an example of a sub-bubble being used for comedy, not for chronology.
Every year you step (back) into a holiday event’s bubble, where real-world time is referred to as if true for everyone in Eorzea. This is the dev. team communicating with you, the player, and celebrating a holiday in-character. And it’s especially true for The Rising, as the Wandering Minstrel is literally in-character Naoki Yoshida. Holiday events aren’t the only place you’ll find player time in motion; Gerolt frequently uses it to mock you for how much time you’ve put into your relic. In Kettle to the Mettle he even refers to the player time between the patch in which Jalzahn first appeared and the patch in which the quest takes place.