Koch Films confirmed absence of English subtitles to my question on their Facebook page in this post: TITANE - Jetzt als Download!
I never use these things, I guess there's no direct link to comments.
I'd keep the preorder for steelbook itself and the soundtrack, but it's a score. In the 90's a score was named a score, and soundtrack was a soundtrack, featuring existing songs used in the movie.
Now I don't know. US disc is just $15...