Haiku is a very short Japanese poem with seventeen syllables and three verses each being of 5,7 and 5 syllables respectively. The Haiku was written primarily in Japanese language and the rules applied were on that language.
Now when I want to write the same poem in another language, how to consider the language rules that was originally written for the primary language. We do have an English version of Haiku, but who decided the rules and how? What if I want to write the same in another (existing or constructed) language - how shall I apply that rule to that secondary language?
P.S. Haiku is not alone - we have limericks that originated in England, sonnets from Italy, Doha from India etc.
Edit: From the concerns mentioned in answer of Jay, what I meant was that in each language "syllable" has different ways of syllabification and way of defining or measuring it. Similar is the case for rhyme - we have different concept of rhyme in different languages.. Therefore, surely any spoken language would have concept of syllable and rhyming - but they differ in definition and structure.