The eye design in the promo is entirely new. They don't match up with any character we've seen in the series before.
The options to me are that this could either be a movie only character, and will have nothing to do with Rum or canon, or that it is just something included in the promo to generate hype and won't even be featured in the movie at all.
I think the eyes being Rum would be extremely unlikely for a couple reasons. Not only would it be incredibly odd for them to do such a significant reveal in a promo video, not even an official trailer, and with the information we have on Rum in the manga, but if this truly were Rum, I think it's a bit ambiguous that they even have a prosthetic. There's surely a difference, and the eyes don't really match up with how Goudzou's prosthetic was shown in MK1412, of course, this was done by a different animation studio, and wasn't shown in the manga either, so it's not really relevant either.
Lastly, I really don't think Rum will have two different colored eyes. I think if Rum had two different colored eyes, and one of them was a prosthetic, the rumors wouldn't be nearly as consistent. I think that Rum's prosthetic will be more akin to Goudzou's in that it was more "realistic" looking. It also seems sensible to me that if you were to get an artificial eye, you wouldn't get one of a different color...