You might be able to achieve the first part of your description by some tricky JOIN constructs.
Just access to a non-existing column will fail at generating the Query.
Cascading might be easier (also for maintenance)  by filling a TempTable over several cycles
and so assemble the final result.

I would suggest to create a ClassMethod projected to SQL as Stored Procedure.
then instead of the trick with the switch you just provide the parameters that you really have

to rephrase your problem:
- You look for a way to switch on/off  column 1
so you need a switch:  >>> new parameter 
and use it like this:

... WHERE (0=? OR  column1=?) AND column2=?

if your first param is 0   then 2nd param (for column1) is irrelevant 
if your first param is 1   then 2nd param (for column1) is effective 

so execute(0,a,b)   uses any value of column1
whille execute(1,a,b) filters column1 and column2

the maxSCALE = 18 
see Doc on $NORMALIZE()
used in ##class/%Library.Numeric).Normalize()

/// Converts <var>%val</var> to a normalized value.
ClassMethod Normalize(%val As %RawString) As %Numeric [ CodeMode = generator, ServerOnly = 1 ]
{
s %codemode=$$$cMETHCODEMODEEXPRESSION
s %code="$select($zu(115,13)&&(%val=$c(0)):"""",1:$normalize($decimal(%val),"_+%parameter("SCALE")_"))"
QUIT $$$OK
}

But it is no problem to clone this data tape and write a private one

ah!

So you don't use the Caché provided Default Link generator in SMP !!!
So you get the default of datatype class %Numeric  (=> SCALE=2)

It might be enough to add :

$SELECT(columntype["Numeric":"%Numeric (SCALE=4)",1:columntype) 

It's all under your own control.

And therefore you should edit the generated class and not touch any defaults.
I assume it's the Link Generator that uses SCALE=2 if Oracle doesn't provide anything.

default SCALE=2 for %Library.Numeric  (since ever)
https://docs.intersystems.com/irislatest/csp/documatic/%25CSP.Documatic.cls?LIBRARY=%25SYS&CLASSNAME=%25Library.Numeric
 

it makes sense also to display what you group 

SELECT count(*),substr(TimeLogged,1,7), ConfigName
FROM Ens_Util.Log
where TimeLogged %STARTSWITH '2021-07'
and ConfigName = 'operation_Name'
group by substr(TimeLogged,1,7)

try to check the conditions / privileges / user..... using CPIPE first.
example:  Execute Server Commands from Caché / Ensemble / IRIS