i mean yes, he's Umath, but he's also Umath FILTERED. He's not Urox, Kolat, Humakt, Serenha, or Vadrus. Every generation down is Decision made.
Some say Vinga is Orlanth. Others say she is his child. Both allow for her to be the same as Orlanth Adventurous, theologically. Either she's one generation more specific, or she is a preferred aspect.