I've finally made a template in my #ikiwiki-based website to wrap images in a proper, “semantic” #HTML5 #figure element without having to write too much raw #HTML. I'm now going over all the existing img directives to convert them. The template is designed to be mostly compatible with the img directive to lessen my work, but I'm taking advantage of the review to redo most of my al texts so make them more descriptive and meaningful.
It's a lot of work, but nobody is going to do it for me.