Been doing some reading of the Σουδά and hadn't realised about system of αντιστοιχεία that was used for arranging words (as opposed to alphabetical)
(https://archive.org/details/suidaelexicongr01suid/page/670/mode/2up?view=theater and https://www.cs.uky.edu/~raphael/sol/sol-html/ )
(Apart from quite wanting a similar system in English indices to help look up words..) – it struck me that this must be pretty solid evidence for the preservation of the οι/υ phoneme even into the 9th century and certainly incomplete ioticisation until then.
I realise the Σουδά is quite late, but are there any other available lectionaries or glosses organised with αντιστοιχείαin earlier roman or Hellenistic periods? Just don’t recall seeing the use of αντιστοιχεία ever used in discussions of the reconstruction of the pronunciation of koine Greek.