[Anguirel]

I wouldn't worry about casting used in the merchandise. In the film the poor gormless blondie was cast as "Iorlas", who was mentioned in the book as Bergil's uncle, but played the role of that joker Gandalf talks to at the beginning of the book, called Inborn or something, I think.

The part is therefore pretty much canonical and has nothing to do with Imrahil. I don't think Tolkien would be rolling about in the old necropolis over it, to be honest.