IPA Phonetics VS 1:1 English to Dovanhzul Alphabet

For the word “years” the IPA is transcribed as /jirz/. The Dovanhzul translator uses the English alphabet “s”. But the ‘alphabet’, offered on another page (https://www.thuum.org/learn/grammar/alphabet.php) listed IPA phonetics and the /z/ was not used in the Dovanhzul translator for “years”.

When we transcribe shall we use letter for letter or based on the phonetic make up the phrase? 

Category: Translation