To actually speak about Khalani is quite difficult. Describing its sounds and phonology could be quite a challenge since the Protoss do not really 'speak' but engage in a telepathic communication. This is the same reason as to why humans can understand Protoss speaking or why do Protoss speak in Human tongues. What really happens is that Protoss can perform a kind of communication that goes directly to the brain, avoiding the whole middle step of using a particular 'language'. But we are told Protoss do have a language of their own.
It seems that when Protoss 'think' they think in this ancient language, in the same way that a german person thinks in German or an italian thinks in Italian. This kind of communication would be a previous step to the full telepathic communication they use. So Protoss can alternate between these two kinds of speech.
As they are not actually speaking it is really hard to determine where is the place of articulation or obstruents in such a 'thought-language'. The best idea I had is that these concepts are here viewed as how humans would 'hear' the consonants and vowels and different sounds, and this is based in the canon in-game sentences and phrases (so in this point it can be pretty subjective).
I thought it would be for the best if the sounds in Khalani were not completely impossible to pronounce, since the idea of the language is that it can be used by humans (and therein lies all the fun, also) so I did the best I could with the material I had to devise the grammar of the language to a point that it will not be plainly taken from English but won't be completely impossible to understand. In a previous attempt I did have some very odd constructions which I've discarded in favour of something clearer.