Hello, I have integrated the TTS in an application I'm finishing up, and it works perfectly, in fact the TTS can work offline.
What I do is I have problems is to implement it on a tablet, does not support it, I guess it's because it lacks the necessary files to reproduce the voice.
Pico TTS TTS Service, Latin Input Method ... just do not know if a file is missing more, but I do not care much about that my application is oriented with telephone terminals, and these terminals almost all bring those files.
Well in conclusion, that to work on the tablet will need to find out what are the applications that handle voice play.
Regards