Alt text are garbled when exported PDF from Word file

Hi,

I have some Chinese documents with ALT text, but after using Acrobat to generate PDF, all the ALT texts in the PDF are messed up, into a similar "Ç°ÊÓͼ" text. How can I fix this situation? 

FYI, not only Chinese documents, we need to translate more than 30 languages, and ALT text in 12(Bulgarian, Arabic, Thai... ) of them cannot be displayed normally.