I was taught the word for godmother was spelled "νουνά" (same thing with νουνός for godfather). Is this an acceptable alternate spelling...or have I been spelling it wrong my whole life?!
Yes, very rarely you would hear someone saying "νουνά" and probably this person would be old. Other than that is sounded a bit funny to me in the few cases i have heard it.
Same for me! Perhaps because I am 58 and my grandparents came from Greece in the early 1910s so the Greek they passed on to all of us would be outdated.