So if the identity of the Queen of Wonderland was not something Surprising and Deeply Significant, they wouldn't have hidden her face. Who, then, could it be? I see three possibilities:
- She's a copy of Regina
This is suggested by the fact that a) the Queen of Wonderland had a vault very much like Regina's vault of hearts, and b) that she didn't want to hear Regina being referred to as the real Queen (in an "I'm the real Regina!" sort of thing).
- She's Regina's mother
Regina's mother doesn't show up in the most recent fairy-tale land stories, and we know that Regina resents her deeply (hey, who wouldn't), so odds are that Regina must have gotten rid of her somehow after they all moved to King Leopold's castle. On the other hand, Regina's mother is magic and therefore probably doesn't get killed off very easily; perhaps Regina got rid of her by banishing her to Wonderland? Which would also explain why Regina doesn't want to meet up with the Queen in Wonderland, and also wants to hightail it out of Wonderland as quickly as possible.
- She's Snow White's mother
Could Regina's mother have had an even wider-ranging plan for her daughter than we thought? That not only did she arrange for Snow White's horse to spook at the right moment for Regina to save her and come to the notice of King Leopold; but that she also got rid of Snow White's mother in the first place? And not by killing her (although her husband and daughter obviously were made to think she died) but by banishing her to Wonderland? This would explain the Queen of Wonderland's refusal to hear Regina being referred to as the real Queen, because obviously Snow White's mother's rightful place is as Queen back in fairy-tale land.
The speaking-through-a-horn thing is weird, too. Maybe, whoever the Queen of Wonderland actually is - was damaged in some way and now her voice doesn't work properly? Perhaps she was burned, so that her face is hideous (hence the veil) and her larynx was fried so she can only whisper?
Just some thoughts!