Tested on http://demo.plone.org/. It looks like these are setting a padding-left value which is stripped on save. Anyway to configure these to be usable?
I already submitted an issue in CMFPlone for the similar strikethrough problem https://github.com/plone/Products.CMFPlone/issues/3069. I don't know if there was a significant change in TinyMCE versions from 5.1 to 5.2 or if it was the relevant Plone framework that changed, but these were definitely working in previous versions.