reproduce scenario is so easy.
open the designer and put a "task node" on canvas,then double click on the "Task node" to give a name. now don't use english keyboard for naming,so use another language for example Farsi(or Persian) and type a name for the "task node". if you save this simple diagram and reload it again, the given name is not what you typed!!!
so I think there must be a way to use utf8 encoding method to solve this problem but have no idea how can I use utf8 encoding in designer 2.1.