Great post, Platypus. I'm framing it!!
I'm using the same line of reasoning in helping DS what is going on for him in school. It's really difficult on self-concept when these kids hit the level of their EF/language issues incompetence. OTOH, I'm trying to be grateful for this happening before college, so maybe we can do something to help.
Mine has developed some maladaptive coping skills (pretend not to care at school-fall apart at home).
I think the serious asynchrony requires a custom balance between challenge and scaffolding. This is not easy!
As for "degree/slope" of (really, any) E--those mild, moderate, severe designations are so influenced by environmental factors. And who is doing the deciding. It's a tough call.
