Did I translate this right?

[Unilsrewtu]

Would 'underground' in Na'vi be 'äo-kllte' ??

[kewnya txamew'itan]

Yes it is.

You might want to use double quotes " not single quotes ' in future because in na'vi ' is a letter and it could be confusing. 

[Tsamsiyu92]

äokllte means under ground, but if you were referring to underground as a place under the ground, maybe this would be better:

Tseng a äokllte lu.
Place that under ground is.

And don't use apostropfhes (') as qouting marks, because it's a letter in Na'vi that sometimes also start words ('eveng, 'it, 'ong,...). Use bold text or "s

Eywa ngahu.

[kewnya txamew'itan]

äokllte means under ground, but if you were referring to underground as a place under the ground, maybe this would be better:

Tseng a äokllte lu.
Place that under ground is.

And don't use apostropfhes (') as qouting marks, because it's a letter in Na'vi that sometimes also start words ('eveng, 'it, 'ong,...). Use bold text or "s

Eywa ngahu.

There's a space between äo and kllte.

Also, in the relative clause, tok would be more appropriate as, even if it's only indirectly about position, it is so I'd use tok not lu.

So: tseng a äo kllte tok

[Tsamsiyu92]

wouldnt kllte nead a accusative suffix, since the verb tok is transitive?

[kewnya txamew'itan]

No, because it has taken an adposition.

Adpositions are never used with a case, they function as a different argument from the direct object.

An example of why no accusative would be taken can be seen with this sentence, oel fìtsenget mì na'rìng tok, when we just say I am in the forest we're just implying a fì/tsatsenget and so there is still a direct object.

[Unilsrewtu]

Alrighty thanks guys I just wanted to see if I put it together right.