It sounds like a perfectly reasonable accommodation. It sounds like you will be able to complete work tasks and stay on top of things with working remotely one day a week and it sounds like you have a proper diagnosis with all necessary paperwork. I see no reason for them to deny it.

Now people often don’t want to ask for accommodation because it means they have to disclose their disability to an employer and not everyone wants to do it. So you have to consider what’s important for you. And there are people who believe that having a disability or a health concern means they have rights to receive absolutely any accommodation. That’s very far from the truth. Accommodation has to be reasonable for your position and job description etc and it has to meet bunch of other criteria. Yours is completely reasonable!

Good luck. If you don’t mind posting how the meeting goes. Fingers crossed. I have a good feeling about this one