Sokushin jōbutsu gi (Buddhahood Immediately and in This Body); Shō-ji-jissō gi (The Meanings of Sound, Letter, and Reality); Unji gi (The Meanings of the Letter Hūṃ); Konshōō-kyō himitsu kada (Secret Gāthās on the Suvaṃaprabhāsa-sūtra); Kanén no sho (On Encouraging Those with a Connection to Buddhism)
Eijo is of course quite well-known in these parts. I was surprised to discover on Amazon that the first edition was published back in 2010 (?!).
Nonetheless this is an exciting development as Shingon becomes more known outside of Japan.