I think I would personally go with the absolute positioning, only for consistency. You appear to have other places like the icon near the top right part of the page that are also positioned.
I’ll note though that for inline text annotations specifically, I’ll usually use CSS :before and SVG code to do this, because then in places like in a blog, a customer can create an H2 and it will be automatically annotated rather than requiring some form of complex embed arrangement for them to learn.