Actually, by all accounts, the Au Ra come exclusive from Othard, and the implication is absolutely that Yugiri's band of refugees are the first and only contact that Eorzea has ever had with the Au Ra (barring some heat with Ishgard, in the long-distant past). It's a fairly pivotal point, one that I hadn't realized until doing the quests for myself just this week.

You are making this up. It has never been stated anywhere by Dev or in game that the Au Ra are strictly from Othard. Like all of the Spoken Races, they most likely migrate around the world. Yugiri's constant reference to her people and contacts are strictly limited to the Doman people which so far have been only Hyur races.

Rogues and Ninjas are a bit different, as Rogues are implied to exist within Limsa Lominsa for a long time, although Yugiri definitely heralds the introduction of proper Ninjas to the world.

Rogues didn't exist until 2.2's reference though. Before then, they did not exist and the style was exclusive to Thancred and Yugiri who don't seem to recognize you as also using their style.

Yugiri's introduction also doesn't herald True Ninjas into the world with the "The Ninja trainer moved there from Doman years before the conflict that brought Yugiri's people to Eorzea" Errata'd into the story.

This already conflicts with Yugiri's story more than the Au Ra will ever conflict because according to Yugiri there are no Ninjas in Eorzea before 2.2's scene and quest where she goes to teach the Rogues the way of her people.

he difference I see there is, the story doesn't expressly say "Ninjas don't exist yet", whereas the Au Ra, Yugiri is fairly clear on the matter, which is why she feels the need to hide her appearance.

It has ** Never ** been stated that her people do not exist. You are forcing out your opinion on an interpretation you made and passing it off as a fact. She can have hundreds of other reasons to hide her face from everyone outside of her race. She feels the need to hide something that is the only fact about that. What she is hiding or why she is hiding it is a speculation. There is no reason for both Yugiri and Thancred to be surprised that they have similar styles in the 2.2 story after 2.4's release because both Rogue and Ninja are open to the players and the style is obviously known to others.

There was no illusion set to be shattered. They aren't in the game now because they aren't available to the players. When they are available the chances of Au Ra appearing through out Eorzea as new NPCs is pretty high.

It makes less sense that the Au Ra's appearance would be more lore breaking than Rog/Nin's appearance with the main scenario completely ignoring that they already exist when you do older content. Yugiri isn't the spear head into the creation of the Au Ra nor is she the reason they'll all start to migrate over into Eorzea. They aren't going to change the opening script more than adding the character data for the Au Ra to appear in the opening sequence.

You'll be able to play as an Au Ra and become a Ninja and do the Main Scenario quest where they'll completely ignore both issues.