using regexp_instr to compare values, need a little help in Oracle Sql

  SELECT a,
         b,
         MAX(
             CASE
                 WHEN REGEXP_REPLACE(
                          REGEXP_SUBSTR(
                              a,
                              '[^,]+',
                              1,
                              COLUMN_VALUE
                          ),
                          '[^' || b || ']'
                      ) = b
                 THEN
                     'good'
                 ELSE
                     'bad'
             END
         )
             c
    FROM (SELECT RTRIM(REGEXP_SUBSTR(REPLACE(a, ' ', ''), '([MWTRFS]+[0-9]+,?)+'), ',') a, b, c
            FROM yourtable) x,
         TABLE(
                 SELECT COLLECT(LEVEL)
                   FROM DUAL
             CONNECT BY LEVEL <= LENGTH(x.a) - LENGTH(REPLACE(x.a, ',')) + 1
         )
GROUP BY a, b

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SELECT a,
       b,
       GREATEST(
           CASE
               WHEN REGEXP_REPLACE(
                        REGEXP_SUBSTR(
                            a,
                            '[^,]+',
                            1,
                            2
                        ),
                        '[^' || b || ']'
                    ) = b
               THEN
                   'good'
               ELSE
                   'bad'
           END,
           CASE
               WHEN REGEXP_REPLACE(
                        REGEXP_SUBSTR(
                            a,
                            '[^,]+',
                            1,
                            1
                        ),
                        '[^' || b || ']'
                    ) = b
               THEN
                   'good'
               ELSE
                   'bad'
           END
       )
           c
  FROM (SELECT RTRIM(REGEXP_SUBSTR(REPLACE(a, ' ', ''), '([MWTRFS]+[0-9]+,?)+'), ',') a, b, c
          FROM yourtable)

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MW56,R123,F34	M5	good
MW56,R123,F34	M6	good
MW56,R123,F34	W5	good
MW56,R123,F34	W6	good
MW56,R123,F34	R1	good
MW56,R123,F34	R2	good
MW56,R123,F34	R3	good
MW56,R123,F34	F3	good
MW56,R123,F34	F4	good
.
MT567	W5	bad
MT567	W6	bad
MT567	W7	bad
.
MF1,MWF3	M1	good
MF1,MWF3	M3	good
MF1,MWF3	M6	bad
MF1,MWF3	T6	bad
MF1,MWF3	W3	good
MF1,MWF3	W6	bad
MF1,MWF3	R6	bad
MF1,MWF3	F1	good
MF1,MWF3	F3	good
MF1,MWF3	F6	bad

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drop table event_days purge;
create table event_days(event_id number, series_id number, day char(1));

drop table event_periods purge;
create table event_periods(event_id number, series_id number, period number);

--MWF23,R34,T10,F5
insert into event_days values(1,1,'M');
insert into event_days values(1,1,'W');
insert into event_days values(1,1,'F');
insert into event_days values(1,2,'R');
insert into event_days values(1,3,'T');
insert into event_days values(1,4,'F');

insert into event_periods values(1,1,2);
insert into event_periods values(1,1,3);
insert into event_periods values(1,2,3);
insert into event_periods values(1,2,4);
insert into event_periods values(1,3,10);
insert into event_periods values(1,4,5);


--MTWR1256
insert into event_days values(2,1,'M');
insert into event_days values(2,1,'T');
insert into event_days values(2,1,'W');
insert into event_days values(2,1,'R');

insert into event_periods values(2,1,1);
insert into event_periods values(2,1,2);
insert into event_periods values(2,1,5);
insert into event_periods values(2,1,6);
commit;

create or replace view event_vw as
select ed.event_id, listagg(days_for_event || periods_for_event,',') within group(order by case substr(days_for_event,1,1) when 'M' then 1 when 'T' then 2 when 'W' then 3 when 'R' then 4 when 'F' then 5 when 'S' then 6 end) event_list
from
	(
	select event_id, series_id, 
		listagg(day) within group (order by case day when 'M' then 1 when 'T' then 2 when 'W' then 3 when 'R' then 4 when 'F' then 5 when 'S' then 6 end) days_for_event
	from event_days ed
	group by ed.event_id,ed.series_id
	) ed
join
	(
	select event_id, series_id, 
		listagg(period) within group (order by period) periods_for_event
	from event_periods ep
	group by ep.event_id,ep.series_id
	) ep
on ed.event_id=ep.event_id and ed.series_id=ep.series_id
group by ed.event_id
/

select * from event_vw;

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M1,WF1	        M1	good
M1,WF1	        M10	 bad
M1,WF1	        W1	good
M1,WF1	        F10	bad

M10,WF10	M1	good   <-- this should not be good !
M10,WF10	M10	good
M10,WF10	W1	good  <-- this should not be good !
M10,WF10	W10	good

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M1,WF1	            F10	bad
M1,WF1	            M1	good
M1,WF1	            M10	bad
M1,WF1	           W1	good

M10,WF10	   M1	bad     <-- correct !
M10,WF10	   M10	good
M10,WF10	   W1	bad       <-- correct !
M10,WF10	  W10	good

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but in our system that COULD be recorded