Still, it's clear that Wulfila chose a lot of his spelling conventions based on those of Greek. Using 𐌴𐌹 to write a long [iː] was certainly one of those conventions, and another clear example is using 𐌲 to represent [ŋ]. He couldn't have based his choice of 𐌰𐌿 on Greek (because there it was becoming [af] rather than a long vowel), but for 𐌰𐌹 he probably was inspired by Greek. So what sound was αι in the Greek of the time? Was it higher than ε or lower? The page Koine Greek phonology shows that both were in fact homophones and had been already for hundreds of years before. So if he took those two writing conventions from Greek, he did not take their pronunciations as they are different in Gothic. That means that we have to derive the pronunciations of those two vowels from loanwords. What letters does Wulfila use to substitute for η in Greek loanwords? And what about Latin, which he no doubt knew as well? The Latin of the time had ĕ [ɛ] and ē [e], length distinctions were probably disappearing (see Vulgar Latin). So what does Wulfila use for these two Latin sounds?