Bueno, pues la propia Criterion confirma que sólo habrá subs en inglés. Mandé un mail a un tal Jon Mulvaney (especie de relaciones públicas) y me ha contestado que por temas de derechos sólo incluyen subs en inglés.

Copio y pego el mail:

Hi Enrique,

Thank you for your email!

I'm sorry, the THE THIN RED LINE Blu-ray release will only include English subtitles as our rights are limited to to North America and therefore, we are generally only licensed to include English language subtitles on our DVD and Blu-ray releases. Unlike most other Criterion discs, all authoring, replication and distribution of THE CURIOUS CASE OF BENJAMIN BUTTON is handled by Paramount. Hollywood studios such as Paramount generally control world-wide rights, so this is why the release of this DVD includes Spanish subtitles as well.

I hope this information is helpful! Please feel free to let me know if you have any other questions about Criterion!

Best,

Jon Mulvaney