The Turks are the weirdest civ we currently have. They have weird UU and UP. They cover a really big area, but never united under single state(except under Mongols). I think there's a lot of their aspect needing attention right now.
Historical Area
Most Russian/European Turkic territories like Bulgaria, the Pontic steppe, Volga, Crimea, and Sibir are missing from the historical area. Are the ingame Turks only represent the Gokturk and Seljuk empires?
Will there be a separate civ for the Western steppe people, or they will simply be barbarians?
City Names
Lot of tiles in Central Asia have no city name right now. Some important Turkic cities(which I found randomly in Wikipedia) currently missing on the map including:
Balanjar, Samandar, Qashliq, Tyumen, Pliska, Sredets(Sofia), Bakhcisaray, Balasagun, Turkistan, Qirim, Tmutarakan and Astrakhan.
Some would overlap with the existing Turkic name though. I'm no expert at geography so I can't make a proper city name suggestion yet.
On the CityNameManager, Turks should also have iLangMongolian to make up for their lack of city name especially around Altai and Eastern Asia.
UU
I love the Oghuz, but i also feel bad to use them. Jumping from one friendly city to another into deeper territory, pillaging and kidnaping their workers, then hide back into their cities feels more like a spy than a barbaric raid.
But removing their infiltrator ability will make the UHV1 impossible though. And I'm not really fond of their name, a generic name like "Oghuz Archer" or "Oghuz Raider" would still sound better than just their ethnicity.
Anyway, I have an idea for secondary Turkic UU.
Nomad (replaces Settler)
Movement: 3
Strength: 4, but can only defend
Can build Pasture faster than Worker / Cities built on resources also give pasture yield
Also spawns as barbarian in Central Asia(and Sahara?) and can be captured with the Turkic UP
The first Turkic UHV suggests the player to recreate the Gokturk Khaganate at its glory in addition to western Turkic states like Khazar, which means you need to settle 5 to 7 or more cities.
But the poor, unimproved lands of Transoxania(in 600AD start) means you cannot build enough settlers in time, leaving the only viable but ahistoric strategy is pushing your armies through India and Middle East too early.
Having fast, capturable Settler replacements not only help you settle the 6% area early, but also portray the "unifying tribes" vibe of the Turks without the need of placing independent cities. They can also become free Worker source for other civ, or when the Turks under peacetime.
I give them minor strength so they are slightly harder to capture(turn into worker) by other civs. I mean, you are fighting not just stray worker but a whole nomadic community.
I also suggest the pasture ability so the workers can focus on building roads and plantation(and to work that Orduqent camel tile

).
Tech
Give them Politics, so they can choose Elective on the first turn and to give them a bit tech trading advantage over Arabs.
Should we also reduce their Research Cost modifier a bit? Mongols have 90 ResearchCost so the Turks deserve 100 at most.
It won't hurt to give them better tech rate. The Turks were also part of the Islamic Golden Age, so having your tech rate go rocketing once you control the Middle East is still historically makes sense.
In a more extreme suggestion, i would suggest separating the Turk into two civs. The nomadic Turks will represent Cuman, Bulgar, and Tatar in addition to Gokturk. And a new Turkoman civ to represent Turkestan-based states like Seljuk, Timurid, and Uzbek.
This way the Turks could have most of the Eurasian Steppes in their border in 900AD, getting split eventually into three big empires(Cumania, Seljuk, and Mongolia) in 1200AD, then getting invaded and respawn in Eastern Europe as the Golden Horde.