From what I can tell, yes they do use real words. I remember reading somewhere that for “Duel of the Fates” (Star Wars: The Phantom Menace):
The lyrics were taken from one line of the Celtic poem “Battle of the Trees” loosely translated into Sanscrit.
Khara Matha Khara Rath Amah
Khara Rath Amah Yuddha Khara
Khara Syada Rath Amah Dai Ya
Khara Ki La Dan Ya
Niha Ki La Khara Rath Amah
Syada Ki La Khara Rath Amah
Khara Dan Ya Khara Rath Amah
Khara Dan Ya Khara Rath Amah
Niha Ki La Khara Rath Amah
Syada Ki La Khara Rath Amah
Khara
Khara Matha Khara Rath Amah
Khara Dan Ya Khara Rath Amah
Niha Ki La Khara Rath Amah
Syada Ki La Khara Rath Amah
Khara
What the words mean:
Khara = dreadful
Matha = head
Rath = speak
Amah = give
Yuddha = battle
Syada = raging
Dai = purify
Ya = going
Ki = like
La = taking
Dan = separate
Niha = loss
The line from the original poem reads, “Under the tongue root a fight most dread, and another raging, behind, in the head.”