Mushki is attested twice in Urartian texts. Both are from Rusa son of Argishti period. They are attested in an atypical text where a list of eight countries is mentioned. The text do not describe a specific campaign but rather is a summary of numerous campaigns, while the eight countries are the most distant places where Rusa's army reached moving in all directions.
Here is the raw text.
mru-sa-a-še mar-giš-te-ḫi-ni-še a-li pa-ru-ú-bi LÚ MUNUS.lu-<tú-ni>
KUR.tar-gu-ni KUR.e-ti-ú-ni-ni KUR.tab-la-ni KUR.qa-i-na-ru-ú KUR.ḫa-a-te-e KUR.mu-uš-ki-ni KUR.ṣi-lu-qu-ni-ni
Rusa, son of Argišti, says: I deported men (and) women from the enemy countries, from the land Assur (Assyria), from the land Targuni, from the land Etiuni, from the land Tabla (Tabal)), from the land Qainaru, from the land Hatti (i.e. the Neo-Hittite states), from the land Muški, from the land Ḫatti, from the land Ṣiliquni.
Now let's locate this countries. And their direction relative to Biaina.
Assyria - south
Targuni - unknown but if is equal to Derjan then north west
Etiuni - north east
Tabla - west
Qainaru - south?
Hatti - west , west-south
Mushki - ?
Siliquni ( Syunik ) - east
As You can see the translator arbitrary added the second Hatti after the Mushki based on the assumption that Mushki was in Hatti. In the raw text there are no two Hatti. Mushki is just another country as others so it can have any direction. So what was this direction?
Well given the logic of the text were eight countries are mentioned and for each four side of the world we have one pair of two countries we can deduce that Mushki was in North west side of Urartu. Placing them in the West would mean that the scribe mentioned three countries in the West leaving the the north/northwestern side with just one country (Targuni). How to check this? Well let's look a similar text but with little bit different set of countries.
mar-giš-te-ḫi-⸢ni⸣-še a-li pa-ru-bi LÚ MUNUS.lu-tú-ni
KUR.tab-la-a-ni [KUR].qa-i-na-ru-ú KUR.mu-uš-ki-ni KUR.ḫa-te-e ⸢KUR.ḫa-li-ṭu⸣
This time the text is broken. Only six name are readable. It looks two are missing (Assyria and Etiuni?). The rest is similar except there is a new country Khalitu instead of Targuni. Khalitu is almost certainly the Armenian Khalti-k' which is unambiguously placed in north western direction relative to Biaina. So the assumption that Targuni was in North West was correct. Once more we have two countries in the West and it would make sense that Mushki was near Khalitu and NOT near the Anatolian group (Tabla, Hatti).
This location in the North would be fully consistent with Greek sources placing Mosch-oi ( Mushki) in Pontic region or near Meschetian mountains.
If new inscriptions with the term Mushki reinforce this location then we will have another hard evidence that early Iron Age Mushkis mentioned by Assyria were initially from North Eastern regions of modern Turkey.