[Quoth]

I'd never use tables (or frames) for lists. A <p class="my-custom-list-1"> etc works fine and renders on epub2, and converts to azw3/KF8 or KFX or epub3.

Indeed I avoid tables, and on epistolary content from Gutenberg I convert the two columns to alternating paragraphs, which is easier to read. That's less than ideal for bilingual texts that use facing pages (only works on PDF & Landscape tablet) or columns in a table, but actually works on a smaller (anything less than 8″) screen.

Automatic from a docx paragraph style in LO Writer without using "list" property via Calibre.