Completely agree with the preference you stated.
As for framing it, a good approach can be to use questions like "how does she do when things are more quiet?" "Since she doesn't have issues when things are more quiet would you consider doing X, instead?" With a lot of steps from the first question to the second so that the teacher has the chance to get the light bulb moment on her own.
If that isn't working, I've had luck with framing the statements more as "this is what I've found works for me, and what does not work for me."
Long run the teacher will be more interested in a successful outcome than in being right, but the road to get the teacher to the right place does need to be gentle; they face far too many people every day telling them all they do wrong.
Good luck!
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Mom to an amazing young adult AS son, plus an also amazing non-AS daughter. Most likely part of the "Broader Autism Phenotype" (some traits).