If it's not too much trouble, would it be possible to automatically handle "incorrect table structure" via this plugin? This is one of the most common conversion failures I get on old tech books. Specifically, Kindle Previewer rejects anything that's not in the exact order:
<table>
<thead></thead>
<tbody></tbody>
<tfoot></tfoot>
</table>
For whatever reason it seems like it used to be popular to put the footer before the body and that's a no-go. Simply swapping the order of the elements is enough to get it to pass. It's possible to fix it by hand, but a little tedious if there's a lot of them.