Hi Richard!
We were asked pretty much this same question just recently:
theeventscalendar.com/support/forums/topic/how-accessible-are-the-calendars-ada-compliance-question
In essence, we are mindful of and work hard to create plugins that are accessible — but there are areas which, currently, may not be fully compliant with standards such as those you noted.
We don’t have an exhaustive list, I’m afraid, and of course different users make use of different facets of our plugins — so for those reasons taking our free core plugins such as The Events Calendar for a spin and evaluating them in the context of your own project is definitely recommended.
I hope that helps – but let me know if you have any further questions I might be able to assist with 🙂