Respectfully I disagree and I am 90% sure the ADA does as well.
One important thing is to understand that there are multiple components to ADA and it is Title III and the ADA Standards for Accessible Design that are usually referenced when discussing public accommodations and actual facilities owned by private entities. Title I relates to employment and Title II to State and Local Governments.
My point is that while Title III does specifically address direct facility and construction related aspects, I do not believe it addresses areas such as audio reinforcement systems or performance lighting systems or their use except in terms of specific requirements such as accessibility and Assistive Listening Systems. The issues of audio and lighting system performance, programming, content, etc. seem to be outside the purview of ADA except possibly as related to employees and aspects directly related to their employment.
Lighting is not elective. Just like sound isn't elective. If someone has tinnitus and the sound is too loud for them, do you turn it down just for them? Nope, you offer them earplugs or a more traditional lower volume service.
I'm not sure I understand your point. Performance lighting and sound are elective in terms of both the systems and the especially the systems' operation and related content. I think the whole point here is that other than the few specific ADA requirements which do not even apply to many churches, your lighting and sound systems and how you use them are completely discretionary. You may choose to use certain design elements or operate the systems a certain way but those are all discretionary choices.
Given that, while I fully embrace the importance of artistic vision, I personally do not understand an 'artist' for a church feeling their 'artistic vision' is more important than the chuch members' safety and comfort. I believe that determining whether a lighting programming cue or the audio levels that cause physical problems for some church members are appropriate is a matter to be decided by church leadership rather than by just the 'artist' or system operator.