about cross languages synthesis

Please, anyone can say something about cross languages synthesis? Is there the function in Audacity? Or you would like to add the function in future? thanks

Do you mean this: https://www.researchgate.net/publication/221482035_Cross-language_synthesis_with_a_polyglot_synthesizer
If so, then no, Audacity does not have any features specific to that are of research. Audacity is a general purpose multi-track audio app for recording, editing and processing audio.