Compare all rows with the same A$, then, for those row results, compare all L$, if all the L$ match, then "Completed"

[IfAndOrWhatAmIDoing]

I'm working on a schedule, and it's gotten pretty complicated (for me anyway) with Tasks with subtasks, dependencies, and etc.
Currently it's setup that I have to Copy/insert a Task+it's corresponding SubTasks for it to function properly, and then I have to go back and manually change the reference in the formula.

What I'm trying to do now is to make each row with formulas that can sustain on their own (and survive copy/insert) without having to worry about copying Task&SubTask together, and without having to manually tell it where a subtasks' Main task is. My obstacle currently it the L Status Row.

So basically, whatever row the formula is on, look at A$, then compare the M$ for all of the rows that have the same A$, and if all of the M$ say "completed" then say "Completed" here too.

I've tried a lot of things, but I haven't been able to wrap my head around a way that works... I'm not sure what the best way to share is, so let me know.
I use an older version of excel, so some functions are not available, and I am trying to stick to purely Excel basic commands, not vba or any other tools..

Portion of the formula I really care about is in Purple: (taken from M12, there's a beginning part to this formula to decide if it should run, or if formula2 should run based on if its a Task or Subtask, but I did not include in the text friendly version bellow)
Text Friendly version (apologies if there are typos):
IF($L$4="Completed","Activity Complete",IF(COUNTIF($L$13:$L$18,"Completed")=COUNTA($L$13:$L$18),"Completed",IF(VLOOKUP($C$12,$A$4:$M$43,12,0)="Begin","Execute Task",IF(VLOOKUP($C12,$A$4:$M$43,12,0)="Completed","Execute Task","Waiting")))

IF SHUTDOWN = Completed, Then: "ACTIVITY COMPLETE"
	Otherwise: IF SubTasks Status for That Task are all = Completed, Then: Completed
		Otherwise: if Dependancy matches exactly something in the RANGE return 12th column if= Begin, Then: Execute
			Otherwise: if Dependancy matches exactly something in the RANGE TurnGreen, return 12th column if = Completed, Then: Execute
				Otherwise: Waiting

Real (and full) version of M12:
=IF(MOD($B12,1)=0,IF($L$4=Tables!$A$4,"Activity Complete",IF(COUNTIF($M$12:$M$18,Tables!$B$2)=COUNTA($M$12:$M$18),Tables!$C$4,IF(VLOOKUP($C12,TurnGreen,12,0)=Tables!$A$3,Tables!$C$3,IF(VLOOKUP($C12,TurnGreen,12,0)=Tables!$C$4,Tables!$C$3,Tables!$C$2)))),IF($M12=Tables!$B$2,Tables!$C$4,IF($L$12=Tables!$C$3,Tables!$C$3,Tables!$C$2)))

A1

B1

C1

D1

E1

F1

G1

H1

I1

J1

K1

L1

M1

Task ID [Color for Partner]

Sub Task

Dependency / Sequence Task ID [Add 2nd Dependancy and change time & status calculation Formulas for it]

Task Duration (Minutes)

Main Task or Sub Task Duration (Minutes)

[Will Delete This, or just extract from G, maybe add a new column to extract time, so G can be hidden when setup]

Scheduled Task Time (Atlantic Time)

Task

Environment

Location

Partner [Conditinal Formating for Partner, (if not complete?)]

Status

Completed

0

0.0

Will Be deleted probably

2022-09-10 0:01

Start Time - Atlantic Time Zone 12:00 AM

Begin Shut Down / Start Up

1

1.0

30

2022-09-10 0:01

First Task, do not copy

Execute Task

1

1.1

5

2022-09-10 0:01

Subtask 1

Execute Task

No

1

1.2

5

2022-09-10 0:01

Subtask 2

Execute Task

No

1

1.3

5

2022-09-10 0:01

Subtask 3

Execute Task

No

1

1.4

5

2022-09-10 0:01

Subtask 3

Execute Task

No

1

1.5

5

2022-09-10 0:01

Subtask 5

Execute Task

No

1

1.6

5

2022-09-10 0:01

Subtask 6

Execute Task

No

2

2.0

1

12

2022-09-10 0:31

All other Tasks

Waiting

2

2.1

2

2022-09-10 0:31

Subtask 1

Waiting

No

2

2.2

2

2022-09-10 0:31

Subtask 2

Waiting

No

2

2.3

2

2022-09-10 0:31

Subtask 3

Waiting

No

2

2.4

2

2022-09-10 0:31

Subtask 4

Waiting

No

2

2.5

2

2022-09-10 0:31

Subtask 5

Waiting

No

2

2.6

2

2022-09-10 0:31

Subtask 6

Waiting

No

Any help greatly appreciated!

 

[IfAndOrWhatAmIDoing]

Typo: Taken from L12 (not M12)