It doens't make sense for a wendigo to be in Texas--the movie's setting. Or in Monument Valley in southern Utah, the movie's actual setting.
It also doesn't make sense for Tonto, supposedly a Comanche Indian, to believe in or care about wendigos. It would be like a Chinese man hunting a Jewish golem. It could happen, but it makes no sense without an elaborate explanation.
I don't know anything about the supposed werewolf subplot. What's left is a villain who's inordinately evil because he's a wendigo--a malevolent spirit in human form. He eats human hearts and massacres whole villages--which isn't much different from your usual mass-murdering bad guy.