There are limitations to the anime that can be accepted to the site, notably there should be significant creative control of the titles from Japanese studios and be professionally produced.
Even if a title is animated by these studios, it may not be added to the site due to significant creative decisions being made by western companies.
RWBY has a Japanese dub and was broadcast on Japanese TV. However, as it was produced by an American company (Rooster Teeth) and its primary staff (director, writers, etc.) are also American, it would not meet the anime criteria for this database.