Problem filtering information in MySQL query
This might be closer:

select  e.EmpName,
        GROUP_CONCAT(r.RoleName) AS roles
        CASE
            WHEN FIND_IN_SET("Chief",   GROUP_CONCAT(r.RoleName)) THEN "BOS"
            WHEN FIND_IN_SET("waiter ", GROUP_CONCAT(r.RoleName)) THEN "CHA"
            ELSE                                                       "CUS"
        END  AS Profile
    FROM  EMPLOYEE AS e
    JOIN  EMPROLE  AS er  ON e.EMPLOYEEID = er.EMPLOYEEID
    JOIN  ROLE     AS r   ON er.ROLEID = r.ROLEID
    group by  e.EMPLOYEEID;


Notes:


Please use the JOIN ON syntax instead of commajoin and WHERE.
The GROUP_CONCAT occurs 3 times; that can be avoided with the expense of a nested query.  I did not think it was worth it.
Be sure to have something like this on EMPROLE:

PRIMARY KEY(employeeid, roleid),
INDEX(roleid, employeeid)