I tried transliterating "yes" for Japanese and Spanish. I'm pretty sure the Japanese don't say "hai" as in "Hai gurlfrand, how ya durin?"
If you transliterate the English "yes" into Japanese, you get イエス (iesu), which reads like ee-ess.
If you transliterate it into Spanish, you get "yes", which reads like "yes" because both languages use the roman alphabet. Also "si" is a lot more obnoxious than "yes".
What are you talking about?