In the ideal world all the fuel levels would be the same.
I would make sure the fuel levels are sufficient to have all the jets immerse in fuel. Idle jet is shorter, don't want it starved.
Next level of concern would be effects on cruise mixtures. This would be observed as variations in spark plug deposit colors.
Now that you know the fuel levels, see if that corelates with lighter colors on the lower level carbs. If not, no worries. If so, adjust the levels on the carbs for the cylinders you wish to improve.
Cheers,