Thanks for your reply.
I’ve been learning and testing the features of the SDK by designing an epub reader and my “beta testers” are older persons, but only speak Spanish and not English. Whenever I do tests with them I have to tell them how to sit in the best position. I only thought that if they start calibration without anyone who speaks English, can they have a problem to read the messages on the screen.
It was only a question because I think it would be interesting to have this functionality in the future. Maybe other developers have asked about this issue.