Just wading in here as someone who works with adults with learning disabilities
I think Ellie did remarkably well yesterday to manage that environment for such a long time, especially as people with down syndrome often will have sensory processing challenges. That environment would be a sensory overload for a lot of people, let alone someone with down syndrome
I think she will be able to handle criticism from the judges. I think the issue will come when the judges comments do not line up with the scores e.g. Shirley telling her she's fabulous and then scoring her a 4. We tend to find it confusing when a judge has no criticism for a contestant yet scores them low, so I can't imagine how confusing it may be for Ellie. The best thing that the judges can do for her is to be honest about where she is, but frame it constructively.
I also think there's a slight overreaction to how Ellie will manage going forward. Yesterday was clearly a trial run, and now I'm sure the team around her will be better equipped to support her during the live shows. The main thing that her team around her should be working with her on is self-advocacy so that she can be more aware of her limits and thus be supported accordingly, as well as helping her with emotional regulation techniques and managing expectations and help her to understand the competition aspects of the show