They grey text shown when submitting a twitter favicon suggests a http://twitterr.com/blah URL, but as Mondo is on mobile this might be confusing as copying from a mobile browser will usually yield a mobile site URL. Perhaps change that greyed out text to the mobile site URL?
I just send through the @name rather than the full URL and that usually works
I imagine it’s a human on the other end, if only to avoid abuse. Though that’s not the point really - it’s more about having a confusing vs non confusing interface.