Hello Well it is well established that Latin fell out of official use in the administration in the 7th century when most of the Latin speaking provinces were lost Africa Spania much of Illyricum most of Italy but already in the 6th century Greek was on the march the Novellae of Justinian for judicial and administrative purposes cf Oxford Dictionary of Byzantium p 1175 on Language Latin certainly survived in isolated pockets in the Balkans the Vlachs as you correctly point out but in no way as an official language And most of the Balkans was from the mid 7trh century dominated by the Slavs and the Bulgars who did not use Latin at all Instead some inscriptions in Greek raised by the first Bulgar monarchs survive Usage of Latin characters in coins is not a convincing argument to the usage of the usage of the Latin language The Byzantines were nothing if not traditionalists especially in matters of imperial ceremonial protocol and representation which includes the imperial coinage If you read the De Ceremoniis you ll find several Latin acclamations preserved in a corrupted form from the 4th 6th centuries but they are exactly that preserved ceremonial acclamations not evidence of a living language The same goes for the coins i e they follow models from the past Latin was only known by a few well educated men by the 9th century and in a very superficial manner by professions were it had survived in terminology i e lawyers and the military in the form of commands As for the transliteration I am following standard scholarly practice in transliterating the diphthongs fully and not phonetically this was used int he article before mind As for empty boxes instead of some of the Greek letters I don t understand what you are referring to Best regards