ADA requires the school to give the student reasonable accommodations, if the school finds the request is warranted. If all upper class housing is full by the time the request was made, it may not be possible to meet this request. If there are kids in forced quads or triples, it may be school policy to undo those arrangements before giving a student a double as a single. If the school finds that the need is valid, the ADA appears to say this student should be placed on a priority list for the next single that comes up (after any other kid with a verified need already on the list is accommodated). I don’t think ADA requires the school to force a kid in a single to switch to a double or force a kid in a double to move to a triple. Hopefully, by the spring she can be moved, perhaps to a single where the student is going abroad.
I think you have explained your daughter’s needs well. It may be difficult to prove this is a need the school find is within the disabilities covered under the ADA. I really hope things improve for your daughter.
Barrier free access is difficult to retrofit on existing buildings. I would doubt a lot of college students will sue over the issue because by the time the suit is complete, they will likely have graduated from another college. What are the damages? There absolutely should be requirements that the best effort is made to provide barrier free access, but it may not be possible at every single building in every school.