Looks great and good choice for tank. The hornwort will be good as she can suspend herself and rest in it. I think the flow thing is a over worrying.* Is that Eco-Complete substrate? If so you could add Amazon Sword plant and Christmas Moss ball. I would add an Indian Almond Leaf, let it sink and release it's tannins and other stuff to improve the health and protect from disease.
*(I'm still a newbie) My Betta like hanging around in rough waters if there is a place with no flow as well. My personal opinion is Betta have been raised in little cups and jars and are seriously out of shape.
“What should young people do with their lives today? Many things, obviously. But the most daring thing is to create stable communities in which the terrible disease of loneliness can be cured.”
― Kurt Vonnegut