Transliteration is a type of conversion of a text from one script to another that involves swapping letters (thus trans- + liter-) in predictable ways, such as Greek ⟨α⟩ → ⟨a⟩, Cyrillic ⟨д⟩ → ⟨d⟩, Greek ⟨χ⟩ → the digraph ⟨ch⟩, Armenian ⟨ն⟩ → ⟨n⟩ or Latin ⟨æ⟩ → ⟨ae⟩.
Transliterations are designed to convey the pronunciation of the original word in a different script, allowing readers or speakers of that script to approximate the sounds and pronunciation of the original word.
While differentiation is lost in the case of [i], note the allophonic realization of /k/ as a palatalized [c] when preceding front vowels /e/ and /i/.
Still, most systems of transliteration map the letters of the source script to letters pronounced similarly in the target script, for some specific pair of source and target language.
Transliteration may be very close to letter-by-letter transcription if the relations between letters and sounds are similar in both languages.
A transliteration would render them all as ⟨au, eu, iu⟩ no matter the environment these sounds are in, reflecting the traditional orthography of Ancient Greek, yet a transcription would distinguish them, based on their phonemic and allophonic pronunciations in Modern Greek.
This sound is not present in most forms of English and is often transliterated as "kh" as in Nikita Khrushchev.