I see the rusty bracket in the photo but don't quite understand the question. Have you tried popping off the plastic end caps (which I believe are simply clipped on) for access to the hardware underneath? Sorry, haven't had to mess with the wiper mount myself, although I have removed the right-side wiper completely many years ago and drive without it.
I tried looking up the workshop manual, section GR00004900-51.pdf, which devotes over 40 pages to the wiper but doesn't offer the detail I think you're asking for, although they do have a nice exploded view on page 51-44.
I don't know if this link still works for the manual:
