Hello peiyouliao,
Sorry for late reply to this,
I have checked in your site, it seems like because of us move all the apps language string file to
en-GB.com_easysocial.ini, so the system still get from the apps language string file, I have help you removed those apps language string file from your backend, every language string is refer on your frontend now.
Please have a check, it should fix this issues already.