Dear Community,
I have multiple columns having numeric (Type- Double) columns, I want to check validity of each column like length, not null etc. Using Formula tool, unable to implement multiple columns like 100 columns.
So used Multi-Field column as below-

IF Not (IsNull([_CurrentField_])) AND IsNumber([_CurrentField_])
THEN 'Data source value is valid'
ELSEIF IsNull([_CurrentField_])
THEN 'Data Source Value is empty'
ELSEIF Not IsNumber([_CurrentField_])
THEN 'Data source value format is incorrect'
ELSE 'Data source value length is incorrect'
ENDIF
I am getting error because input columns are numeric and am trying to create string field for output as below:

Is there any way to achieve this, that proper message will display and string columns can generate to check validity of data.
PFA workflow (small implementation) and suggest the solution.