Since the What's Playing article made it a point that none of the actresses listed are American, I assume we're not talking about Lana as the main lead if she's in the film at all. Pretty much the same position as Lois as far as we know.
I'm guessing this unknown female character will be someone Clark had some relationship with between Lana back in Smallville and Lois in Metropolis. Which city or cities this happens? We don't know yet. We could be dealing with a Lori Lemaris type of situation.
With this, over the course of the film(s), we can see Clark grow not only simply in the aspects of natural growth as a person or a superhero, but in his relationship with loved ones rather than sticking with only one girl or pining over her all the time.
Of course this could all be wrong and moot. Just simple speculation.