Hello,
Strange, this issue was fixed in latest version of EasySocial. Can you check this file 'JOOMLA/administrator/language/en-GB/en-GB.plg_fields_user_joomla_password.ini' and see if you have the below language strings?
PLG_FIELDS_JOOMLA_PASSWORD_TOO_SHORT="Password too short."
PLG_FIELDS_JOOMLA_PASSWORD_TOO_LONG="Password too long."
If no, then you might want to manually add the above strings