Here's what I can tell you:
雨夜 as Amaya is a pretty intuitive pronunciation. "Ame" (ah-meh) is the vocabulary word for "rain," but in compound words, "ama-" (ah-mah) is usual. No problem there.
夜 as a vocabulary word is usually pronounced "yo" or "yoru," but its Chinese (on) reading is "ya," so it works as well.
雨夜 as a vocabulary word is pronounced "amayo" and means "rainy night." Amaya is not a vocabulary word.
My Japanese first names dictionary includes Amaya, but with only three spellings: あまや (hiragana), 阿麻弥 (phonetic kanji), and the third is 雨夜. This implies that it is very rarely used as a given name. If it were common, there would be many more variations.
As a surname, Amaya is usually written 天谷 "heaven/sky" + "valley," which obviously has no connection with 雨夜. Surnames are almost never given as first names in Japan. In my opinion, it's highly unlikely that Western usage of Amaya or Amaia has anything to do with the Japanese surname. If it did, I would think a meaning such as "heavenly valley" would have been suggested.
This message was edited 5/12/2019, 5:53 PM