I was mentioning this thread to a buddy of mine who is orig from Germany & even older than me! He recalls singing "falleri, fallera" as a kid 70some years ago. He suggested that when someone "flipped" the "R" in "falleri, fallera" and it was sung that way, & someone continued the mispronunciation a step further especially when brought to America. Incorrect pronounciation is quite common in America--especially in the "midwest" where I come from.