An interesting point on Ottoman Turkish

Borrowed an Ottoman grammar (Osmanlıca Dersleri I by Dr. Yılmaz Kurt, published by Akçağ) today. I'm surprised I can actually read it in Turkish very well with a dictionary. Now there's an interesting point which has bearings on the relationship between Eski Anadolu Türkçesi, or even Klasik or Yeni Osmanlıca, with Eastern Turkic languages:

ی ye harfi ne zaman u, ü okunur?

Türkçe kelimlerde sonda bulunan "u" harfleri bazen "و" la değil "ye" ile gösterilir.

1: جی : cı, ci, cu, cü eki; Osmanlıca'da her zaman جی gösterilir. قوریجی korucu, قوشوجی koşucu, بوغوجی boğucu, اوچنجی üçüncü کوپری جی köprücü

2: می : mı, mi, mu, mü soru eki Osmanlıca'da her zaman می ile gösterilir. کلدی می geldi mi? اولدی می oldu mu? بولدی می böldü mü?

3: Bazı isimlerde ve fiilerde "u" sesi "ی" ile belirtilir. اناطولی Anadolu, بوری boru, قوزی kuzu, قمری kumru, طوغری doğru, قوری koru, اولدی oldu, صولدی soldu

What I meant by the 'relationship' between Anatolian Turkish and Eastern Turkic languages is that we cannot help but notice the phonetic similarity between orthographical representations of the Ottoman words and those Uyghur words. We know that in Uyghur, suffixes -Ci, -mi and -di (third person singular past aorist) are not influenced by vowel harmony. The vowel remains i regardless of the vowel in the preceding syllable - at least in orthography! Some Uyghur speakers do show a penchant for vowel harmony, especially in pronouncing -mi. But that can also be attributed to vowel weakening, since whereas we observe the distinction i/ı well, lip rouding is always absent, making ü/u impossible. We would assume that in ancient 'careful' pronunciation, the i would have been fully articulated without lapsing into ı.

Now this is what we can observe in Ottoman Turkish orthography: the spelling of those suffixes contradict vowel harmony rules. Since orthography has a tendency to fall behind the development of phonetics, which is what has resulted in the highly irregular spelling spelling systems of English, French and Danish, we can confidently assume that in such languages, the orthography reflects historical pronunciation. Conciliating that with Ottoman Turkish, we can make assumptions on the pronunciation of Old Anatolian Turkish by saying that vowel harmony was not prominent, or at least was not standardised, in those suffixes, by analogy with Uyghur, and people did not feel the need to represent them orthographically, because the phonemes [i], [ɪ/ɯ], and possibly [u] and [y], were treated as the allophones, just as people don't feel the need to orthographically represent the aspirated k (IPA [k] as in 'kite') and the unaspirated k (IPA [k'] as in 'sky') differently in English. This explanation makes sense because we assume that Old Anatolian Turkish was closer to its Eastern cousins than Modern Turkish is.