We had phonetic syllables from the LOTR symphony:
 

The first part matches known lyrics from The Prophecy:

as does the last part:

But the middle part didn't look like the middle section from The Prophecy and this was the part that I never could quite 'hear' when listening to the singing.

Using an Elvish online dictionary, I found the following possible fits for the phonetic syllables

 

Then I made these observations:

Let's throw out nutien.... it can fit but why should it since nothing that is around it is used. Let's go back to Huines as a possibility (the root is huine).

And we see caita used in Galadriel's Lament or Namarie where caita morie means darkness lies... so caita huine would mean shadow lies... extend that to shadow lies on forest region or western forest or western region???

Galadriel does say in the prologue: Rumor grew of a shadow in the East...

The first part is harder... I think noh-ren-nah is two words put together but it's hard to know where to separate the words. We may not get any farther on this section.

But I like:

the shadow lies on the western region

Then Danijel came back with this:

I've solved the mystery of Prophecy lyrics. It was very simple actually :-)

In published sheet music, English lyrics are also published and they are:

Over the land lies the Shadow
Westward it reaches
On Wings of Darkness
The Towers trembles
To the Tomb of Kings
Doom approaches
Out of the Black Years
Come the words
The Herald of Death
Listen - it speaks to
Those who were not
Born to die:
One Ring to rule them all....

So, after all, Marilynn was correct with her assumption that unknown lyrics would mean something like "the shadow lies on the western region". We just have to translate complete section now, but at least we know what it is about. :-)

Later he provided the final solution:

I've tried to reconstruct the Prophecy lyrics and this is the final solution (I hope)

This is phonetic transcription

Lahss-tah
Kweh-tess Eel-fee-ree-mine
Kwar-mah Too-ree-en The
Kawh-mah Too-vee-en
Awr Noh-ren-nah
Kye-tah Noo-tee-en
Noo-men-nah Tahr
Terr-kah-naw Noo-roo-vah
Too-ve-en Kahr-mah Tool-tee-en The
Hoo-ie-ness-she Noo-tee-en
Kawr-mah Too-ree-en The Kahr-mah

First 4 lines we know, also the last 4, but middle part was always a mystery. I reconstructed middle part of the poem. (I used the wordlists from Ardalambion which I'll use from now on because it is the best :-))

[phonetic - Quenya - English]
Awr = Or = over
Noh-ren-nah = Nórena = the land
Kye-tah = caita = lies
Noo-tee-en = nutien is definately wrong, for unknown reason, if you listen to this part it is clearly Huines = shadow
Noo-men-nah = Númenna = westward [Númen (west) + na (to, towards)]
Tahr = Ta = it (my guess is that r is wrongly taken from the next word rahta = reach)

So, this line should read:

OR NÓRENA CAITA HUINES  Over the land lies the shadow
NÚMENNA TA ~ Westward it reaches