Damn sorry you're right, those classes are used for alignment for the image in the text with image element.
Was thinking of these classes for Aloha to support the different list styles https://github.com/neos/Neos.Demo/blob/master/Resources/Private/Styles/_Content.scss
The deprecation warning has nothing do to with it though.
If the text alignment in Aloha generally works, but not for your custom elements, it's likely due to you skipping on wrapping elements for your editable text properties. You need a div or similar tag for the whole element and then a div, span, h1 etc. for each editable text property.