Her theory abut 'sweet' could be justified in in that 'meli' means "sweet" in Greek, and is an element found in many names and words (Melissa, melifluous, etc)
But it is unlikely that Maliyah means all 3 things at once. If it's a Hawaiian-Arabic name (have no idea how this could happen without being made-up), it would mean 'bitter.' But if the 'mal' came from 'mel' it could mean 'sweet'.
"Les yeux sont aveugles. Il faut chercher avec le coeur." -- Le Petit Prince, Antoine de Saint-Exupery