Permalinks when filtering multiple custom post types by single taxonomy

I think you need to add a rewrite rule as the “normal” rewrite rules don’t support your wanted permalink structure. For your use case, you can try it like this:

First: remove the “rewrite” argument from your register_taxonomy arguments (not sure if you definitely need to do this, but it works on my site)

Second: Add the rewrite rule like this in your functions.php

add_action( 'init', 'wpse13483_init' );
function wpse292188_init(){   
    add_rewrite_rule('(events|courses)/accessibility/([^/]+)(/page/?([0-9]{1,}))?/?$','index.php?post_type=$matches[1]&taxonomy=accessibility&term=$matches[2]&paged=$matches[3]','top');
}

Don’t forget to save permalinks after uploading!

Happy Coding!