I was not involved in the Anime/Manga scene so I cannot say for sure, but from my understanding, the people who know Japanese and could translate it from Japane

I was not involved in the Anime/Manga scene so I cannot say for sure, but from my understanding, the people who know Japanese and could translate it from Japanese were the minority. There was a blend of English and Japanese sources in the anime scene though. I don't know the exact mixture. Definitely not for the Harry Potter case. The only source we had for Harry Potter was the English version. It took about 1 day for the English book to be scanned and appear online on KaZaA after the official book release, and leaked versions came up even earlier (but we don't know what was real, many were fanfics and viruses). All translated versions of any language other than English came way later, and as we wanted to consume the books as soon as they were released, English was the only choice.