The problem with Chi is the existence of Chirithy.
Before we learn about 2.5's secret movie, we assumed that Chi is a fairytale rendition of the ancient Keyblade War and the only things canon are the Foretellers, Book of Prophecies, and Chirithy itself (probably).
But the first contradiction occurred in the 1st Anniversary Event, when it is revealed that Chirithy knows who Mickey is. If Chi takes place in the ancient past, how is this possible? Plus there is the scene with Mickey and a black coat figure as well.
Then the secret movie affirmed that the card system Chi used is created from the Book of Prophecies. And also brings about the possibility that Chi itself is a data world. Think of it as a simulation like data Twilight Town. Chi could be a simulation of the Keyblade War instead of a fairytale based on past events.
So here's a problem. If Chi happens in the past, how do you explain Mickey and gang? Treating it as non-canon will void the scene between him and the black coat figure.
If Chi is a data world, maybe Chirithy's role is an administrator or something? Like either Namine & DiZ in KH2 or Data Riku?
I think that knowing solving Chirithy's identity and purpose is the most important thing to learn the truth in Chi. If he is really canon.
What we know so far is that he is created by a master, there is 1 Chirithy per player and is tasked to lead the players in collecting light. Also if the player dies, so does his Chirithy (although we learn this through a death of a NPC who is said to be another player, so it may be a lie).
The latest mission in Chi is about Chirithy discovering a new Heartless (Minute Bomb, emblem) and asked the players to defeat it. After the mission, he told the player to rest for the day and we got the above scene. The dream is incomplete by the way.