First off, I have no idea what is translated to what, or what was the Source Text.

The scenario writers are Japanese, so I am assuming most of the scenario is translated from Japanese to English (and other languages).
But we know that Fern was the one who created the Sylph language, so there are at least some parts that are translated the other way around.
And depending of how they work things might even go back and forth for a while before a final decision is made.

Second, there are a lot of things in the game that are very culture specific. Just think about all the references to songs, tv shows, books, proverbs, etc etc in the names of quests and fates (and sometimes items). We probably wouldn't understand a lot of the Japanese references, while a lot of the English references might be lost on non English speakers. I have no experience with the French and German versions but it is very likely they will have cultural references as well. Simply translating those references would likely make no sense to those reading the translation. So instead many translators opt to replace references with something that their audience will understand. The more you do this the more you approach transcreation as opposed to translation. (a term that was also used, if not coined, by one of the translators of FFX if I am not mistaken).

And, like others mention, different languages work in different ways, and different cultures expect different things. A translation needs to be adapted to appear natural.