Wow, what an excellent experience! There are two identical rooms, so we booked two groups at the same hour from the website, we were in total 9 people, each room allows 6 people... and everybody had a great time! Please go 15 minutes before your scheduled slot because there's some prep and some light hearted role play that gets you in the mood for the night. Nothing annoying, don't worry.
The room itself is fun, not overly complicated. It is possible to ask for an English experience, but in reality besides the introduction, which is pretty standard, there isn't anything that needs Spanish understanding besides maybe two things. Maybe these two things are switched to English if you ask in advance, make sure to ask if nobody in the group understands Spanish at all, but even if only one does is fine is fine, all the puzzles are logical and only two hints require a very simple understanding which is enough to be translated on the spot and never think about it anymore.
The only downside is that we cannot go anymore, unless they change theme. Fortunately they pointed to other places with other rooms and experiences that they recommend.