I am only a lapsed PPL and frequent SLF, so you professionals can shoot me down if you want, but whether he did or did not call three times "Mayday" can and will be established in due course, but is it so important?
I would rather have the successful outcome we all know about, than to hear "Mayday, Mayday, Mayday.... Bang....." on the recordings.
I was taught as a PPL to "aviate, navigate, communicate" in that order.
He "rivered" (can't call it "landed") because he successfully aviated.
He missed some rather densely populated buildings in the vicinity because he navigated.
He let ATC know he had a problem succintly, even if his terminology may in the future be judged to be not quite textbook. ATC seemed to grasp it pretty quickly. Is it not that which counts?
And of course when I say "he", I really mean "they" because he was not alone at the front.
Indeed, the whole team in the aircraft seem to have been pretty good at their jobs.
Heros? No. Just extremely skilled and dedicated and worthy of respect