About the tables created in the richtext editor, each cell should be associated with a header using one of the following techniques :

La balise <th> possède un attribut id unique ;
La balise <th> possède un attribut scope ;
La balise <th> possède un attribut WAI-ARIA role="rowheader" ou role="columnheader".

This is not currently the case, see the code generated for a table created in the richtext editor :

https://accessibilite.numerique.gouv.fr/methode/criteres-et-tests/#5.7