Adeste fideles laeti triumphantes
Venite, venite in Bethlehem
Natum videte regem angelorum
Venite, adoremus, dominum!
In the first link above Luciano Pavarotti, who is from Italy, sings this song in Montreal.
In the second, Helene Fischer, who is from Germany, sings the same song in Vienna.
(Fischer sings exactly the words above, then sings a verse in German, then sings the verse above again.)
Neither of them uses the "soft g" of modern Vatican Latin. In Fischer's case, that's perfectly in line with pronunciations in her native German; in Pavarotti's case it means he is certainly knowingly pronouncing it differently from the way it might be pronounced in Italian. Either way, it's not modern Vatican Latin.
So my question is about the pronunciation of "Bethlehem." As one would expect, Fischer pronounces it just as if it were spelled "Betlehem." But Pavarotti seems to make "lehem" into a single syllable. Would that be condoned by anyone's understanding of classical pronunciation? Or might it just be that Pavarotti has not mastered a pronunciation that is not of a sort occurring in his native language?