the clutches don't really make noise unless they are sticky and squealing, but if they are adding load to the motor that will make the gearbox noisier.

ideally, whatever the clutch material is slips with tiny resistance but manages to spin the thing it connects to at the appropriate time.

some operators used a Teflon disc ... no lube required. An operator in reno used heavy weight transmission fluid in both the gearboxes and on the leather clutches. I'd guess anything that keeps the leather from deteriorating would work ... it's not so much acting as a lubricant as it is conditioning the leather.

in theory neatsfoot compound is formulated to preserve the leather where other stuff ... who knows. I wouldn't be concerned tho, and I wouldn't do anything to the clutches at all...including adding more oil. Let it go for a few months/years and see how it's holding up. Look for leather shavings and try spinning the fan blade with your finger to gauge resistance to slip.