Layout tables are only there to create a certain visual structure. They should not be given a semantic structure markup (such as th, caption, summary, headers, or id) so that they are not read as data tables by screen readers or other assistive technologies.
In the Glossary there are tables elements which only consist of one <th>-element (letters like "A", "B", "C" and so on). Depending on the screen reader or assistive technology, these are therefore read out as extra tables consisting only of a single table header <th>, which can be confusing for screen reader users.
The overarching <table> element should be marked with role="presentation" and the <th> should be replaced with a <td> element.