Finally I ended using (it's also working for different languages of Recaptcha challenges) if someone searches for the same:
">CSS>iframe[src^=' https://www.google.com/recaptcha/api2/bframe ']>FRAME> >CSS>#recaptcha-verify-button"
I was able to do what I want by adding "Execute javascript on element" to loop and then self.parentElement.parentElement.querySelector('span').textContent
But I am still interested if something similar can be done with XPATH or CSS
edit: XPATH syntax is something like this
[[FOR_EACH_CSS]] >AT>[[CYCLE_INDEX]] >XPATH> ../following-sibling::td[1]
now last thing I am missing is how to do it with CSS