Count Across Multiple Columns

Hi everyone,

I'm new to Power BI and having some difficulty doing some analysis:

I want to be able to create a filter of the managers name, that when i select a manager, their top three error codes will be returned.

If there is more than one error listed in "Transaction error code" , the column "Error code for analysis" is multiple, and the errors are split up in the columns "Error code for multiple 1...N"

their are 7 error codes in total:

K1  - incorrect invoice amount entered

K2 - incorrect customer name entered

K3 - incorrect dates entered

L1 - customer account no longer exists

L2 - customer didnt submit all documents

M1 - manager approval pending

M2 - other

Here is my dataset:

Here is our expected output :

Thank You!