Probably. You note that the academics still aren't anywhere close to challenging, so that leaves plenty of cognition left to manage executive function demands that are expected to be much further developed in her grade peers.
In addition, the structures and routines of school can be very helpful to persons with EF deficits, as they help to cue and scaffold. Socially, of course, the milieu is much more fluid, so school doesn't help to structure that as much. And she definitely doesn't fit naturally into the existing social structures of middle school, so neither she nor her schoolmates know automatically what to do with her.
In terms of managing her EF at home, I would consider working on establishing some of those routines (I'm going to assume you have already tried many strategies, probably including some or all of my suggestions below, but FWIW...). Summer is actually a good time for working on imbedding organizational structures for keeping things in their designated places, developing habits of self-care, etc. For example, certain essential activities might need to be done immediately upon awakening, to get them out of the way (e.g., dental hygiene, bathing, eating breakfast). It may help to organize frequently used materials where they are most often used (e.g., laundry basket by the door to bedroom, so that dirty clothes go directly into the basket, not onto the floor).
I would suggest picking a single skill (or cluster of skills, like the morning routine), and focusing on it every day for a month, or until it becomes second nature, then moving onto another concrete skill. Initially, a parent may have to stand over her for the entire process, every single day, then, you may be able to just start her off, wait until it's about half-way through, and then come back in five minutes to check up that she finished, etc., stepping back gradually on supervision.
