The problem here is the sort of problem you always get when you translate a name from one language to another to another. Obviously no two languages have the same sounds, so you always have subtle differences. Concepts translate more easily; I say "chaud" in French, you say "hot" in English, and then we translate that to "Heiß" in German. There's no need to preserve the sounds, you just keep the meaning. But proper names are another matter. Often instead of trying to translate names, you transliterate the sounds.
So in this case, the man in question was known by his friends, family and associates as ישוע (Y'shua) in Hebrew (the traditional ethnic language of Jews; the same name is used in Aramaic, the language people generally spoke in daily life in Judea during the 1st Century).
The Gospels were written in Greek, which was the main language spoken in the Roman Empire. The name "Y'shua" didn't previously have a Greek counterpart, and some of the sounds lacked Greek equivalents (e.g. "sh" was not used in Greek). Therefore the evangelists[1] did the best they could, transliterating it as "Ιησούς" (Iesous).
By the middle ages, Latin was becoming a more popular language than Greek, so most readers used the Latin equivalent. In Latin, the usual transliteration from Greek was "Jesus". The J sound was typically pronounced closer to a "Y" than the modern J, and the last letter was often not voiced, so "Yesu" is a pretty approximation of how their version sounded. But when we get to modern English, we simply use the Latin lettering with English sounds - so the name becomes "Jesus".
So where does the name of the Biblical hero Joshua come into it? Well, there's another peculiarity here. Hebrew is written without vowels in its ancient form. There are little hints that teach you how to pronounce things, but they're complex (my first year Hebrew at Bible college not really being up to the job.
) and not 100% reliable. So whilst you can translate concepts with as good fidelity as any other language (better than most ancient languages), actually reproducing the SOUNDS of ancient Hebrew is problematic. Therefore, the most accurate rendering of the name is "Y - sh - w - 'h". "Yeshua" and "Yehoshua" are both acceptable variants. In Latin, "Yehoshua" is mostly transliterated "Joshua". But the added Greek step leads to a slightly different transliteration of the same name (Jesus). [1] In this context, the word "evangelist" means "one who wrote a Gospel," rather than the current-day meaning of "A person attempting to convert others to a different religion or viewpoint."
)
