I want to add that, other than all legit "realism" complaints, separating Turkish culture from Levantine/Arabs would also have a gameplay benefit of nerfing Ottomans by making them slightly more unstable and harder to manage.
IRL there were several Arab rebellions against Ottoman Empire, especially in Egypt. In eu4? Nah, it's the only great power in game which almost never collapses.
Btw, Turkish culture ATM is probably among eu4 cultures with the biggest amount of development AD 1444.
I don't know how many times you played as Ottomans BUT in the 16th century Mamelukes are revolting in Cairo and Alexandria with big numbers!
They must add "The Celali rebellions" of 17th century in Anatolia.