Originally Posted by
Ametrine
No, this is false.
The Stone and Steel artbook (which I own) has pages dedicated to Viera concept art and entirely seperate pages dedicated to Au Ra art. There are even unique Viera concepts to FFXIV within the pitch, including the possibility of having their alt tribe being similar to Lalafell in proportions to give us another "cute" racial option.
There was never a shift from Viera to Au Ra. They were both seperate races pitched from the get-go, but the devs choose to proceed with the one that became Au Ra for Heavensward, the reason being originality first.
In fact, the Au Ra were referred to as "demon" in the concepts. The proper name came much later.