I'd say this is close to being ready to publish. Some questions/notes:
1. What is the source of the source for Eiji Tsuburaya directing this movie? (Since no page number is given in the citation, I assume none of us own the book in question.) IMDb and Letterboxd have Hiroshi Shimizu in the director's chair instead, although neither of their Japanese Wikipedia pages mention this film. (Ditto Eiji Tsuburaya: Master of Monsters.) If we're going to say without reservation that Tsuburaya directed a kaiju movie before Godzilla, we should be extremely confident in our sourcing.
2. What is the basis for saying Fuminori Ohashi may have played Ravana?
3. Kohan Kawauchi's official site says the film was released in 1941. Might be best to say we're not sure whether it was '41 or '42.