I get that things like "sheets of double glazing" in Domino are hard to sing with conviction and emotion. And "bread bin" is such a mundane object that it too might be tricky....but "undinal"? It fits the melody and timing perfectly and is the perfect word in context of "the siren's call". I'm sure I've heard that Phil won't sing it because be things "undinal" is a word that Tony made up.
Uhhh, this is the same guy who's hit song was Sussudio, yes?