Is it possible for you to change the Theme Properties to Tab Layout instead of Grid?
Also, FYI, I tried to use the field element ebcategory and added multiple="true" so I can select multiple categories. I was expecting it will load Chosen JS but it does not (see screenshot).
I wish you also consider adding more to the theme rendering the xml file fieldset. Instead of hardcode looking for "basic" only fieldset, it will render any fieldset added in the xml file as tab so the settings can be organized according to sections.
Well, if all of this can be overriden, I would already have done it via override but there's no point on doing the change when it will be overwritten on update.