Palm Jumeirah, seriously? Can that even been properly considered as an island? And I don't say that only because I had no idea of that thing's name wathsoever...
2 Ls in spanish makes a "J" or "Y" sound, for americans they would see it as a "Y" but for most other languages they would probably suggest the double Ls to be "J"
2 L's in Spanish makes a "y" sound, not a "J" sound. In Russian the "J" is pronounced like a "Y". I am from Central América so I speak Spanish as a first language. A "J" in Spanish sound more like the "H" in English.
According to Wikipedia both are correct, but Majorca is listed first with Mallorca as the "also" spelling. The name came from Latin, insula major, but the native name is listed as Mallorca. An older spelling was Maiorica. https://en.wikipedia.org/wiki/Majorca
I am not Spanish so this info might not be 100% accurate. however, i have learned much of this language.