Today I ran across キャラクターデザイン (character design) and I found myself wondering why they went with the composite キャ instead of カ, since "ka" sounds more like the "cha" in "character" than "kya" and it's one less kana, which simplifies the resulting word. I google searched カラクターデザイン verbatim and it only gave me two pages of results (none from Japanese sites from what I can tell) against the infinity of results for キャラクターデザイン verbatim, with google also offering to correct the former to the latter like it's a typo.
So either my initial assumption is wrong and カ just wouldn't work in that context, or this is is a "it just is" situation: one of those cases where something that would make more sense isn't done because of arbitrary reasons.
Hence my question: is there any kind of convention, book or authority that regulates how foreign words are transliterated into kana? Would a kid in school be issued a correction by the teacher, were they to transliterate a foreign word phonetically in a way that is understandable but not the commonly used one?
Thanks.
Mod note: I have read the rules and this is not a "what's the difference" or transIation request: it's a question about linguistics and whether one way of transliterating to kana is enforced over the other in Japanese culture.
by GhostSAS