The help tooltips in the preferences, used by the Echo extension are not accessible.
These are being generated by HTMLCheckMatrix in includes/htmlform/fields/HTMLCheckMatrix.php in mediawiki-core. We need to make this accessible. Possibly by using aria-labelledby, see https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/ARIA_Techniques/Using_the_aria-labelledby_attribute and https://www.w3.org/TR/wai-aria-1.1/#aria-labelledby