Let's try some translation

[Mech]

In any case, Earendil in LotR mythology is an immortal sailor who went to the sky and became a star. So he can be referred to as a person, in case Na'vi distinguishes animacy

[Mech]

Here is another attempt. This Quenya phrase is known as Elendil's Oath.

Out from the Sea I have arrived to Middle-earth. Here I will abide and my sons until the end of the world.

Here is the first problem: there are two words for "from", ftu and ta. The first has the explanation 'direction', the other has the explanation 'locative'. Unfortunately there are no examples.

The other problem is some Quenya expression which can't be well translated in English. The phrase starts as "Et Earello...". Et means "out", while Earello means "from the Sea" (ablative). The expression means "Out from the Sea", meaning that Elendil came to Middle-earth from the Sea, which is outside Middle-earth. I am not sure how I can express it in Na'vi.

Here goes:
Ftu/Ta wrrpa txampay p<ol>ate oe ne Entor. Fìtsenge kelku s<a<r>y>i oe sì eveng oeyä vay a kifkey 'i'<ay>a

[Irtaviš Ačankif]

Txampayftu oe wrrpa polate Entorne. Fìtsenge oe kelku saryi oeyä evengsì kifkeyä tì'i'avay.
Using -ftu as a suffix translates the -llo suffix much better.