You could insert the UTF-8 character Zero Width Space to invisible separate your targets from the rest of the text.
You can insert that character by using C-x 8 <ret> zero width space.
This seems the easiest option, but with a tradeof. Because, when introducing a new radio target, you need to do a search-replace operation (to insert those invisible ...
A shorter way to accomplish this is with advice (https://www.gnu.org/software/emacs/manual/html_node/elisp/Advising-Functions.html). Here you can use :around advice to let-bind the variable and then call the original function with its arguments.
(defun silence (orig-func &rest args)
(let ((message-log-max nil))
(apply orig-func args)))