The perfect combination or a betrayal? It's up to you to decide.
www.neogaf.com
I posted the entirety of Tolkien's writing about Helm and this conflict from the appendices in another thread, hopefully linked above. HELM refuses the marriage because Freca, Wulf's father, was untrustworthy. NOTHING is said about how the unnamed daughter felt about it, and in the war that ensues, it's the SONS that do all the fighting. So to inject a female warrior and give her notable events is likely replacing the MEN from the story, not just giving additional actions to the daughter. It's femininst fan-fic, most likely. Would any LESS audience show up if it was just the sons in the spotlight and the daughter was barely mentioned? I suspect just the opposite, if this was billed as a Middle-Earth action film about this struggle and 'Hera' was appropriately situated within the story as the side-character she is, then I think hype would be GREATER. But somehow this thing got green-lit as a "womans story" because they probably are counting on the male LOTR fans to show up regardless (taking them for granted) and want this to appeal to that largely mythical "We want to see women spill blood in battle!!!" female audience.
There are plenty of stories in the Silmarillion that would have broad appeal to men and women, romances across ages, love that stands through adversity, strong women who lead their people through hardship. To twist this one into a girlboss, if that's indeed what they are doing, is wrong and unnecessary, IMHO. It's a valid criticism to level at the project, one they should have anticipated and either accept it or actively market to counter it. But instead the trailer features Hera so thoroughly you'd think she wins the war all by her lithe petite self.