[iudqnolq]

I went to read the page and found them very intuitive. In fact, it took me longer to figure out what you meant by "sidebar elements". I think you meant "sidenote elements".

A very common idiom in long-form webpages is a clickable superscript to show a footnote-like item inline.

To improve usability for people less used to this sort of format I would underline it in blue like a link. I know it's not fashionable, but I think click targets should be styled as either links or buttons and this fits the concept of a link better.

You're completely right the target should be larger. The fix is to add a little padding.