Hello,
Sorry, but the problem isn’t with our theme, but with the code your client is copying. We don’t know how that site is created and why such code is copied. You can recommend him to write descriptions manually.
To fix the errors on category pages you need go to Products > Categories > open category and re-save it. Errors will disappear. The problem is related to changes made in category header editor.
Thank you.
Regards,
Eva Kemp.