It is only meant to drain out any water or condensation....... but........ the orings around the valve cover do fail as the get old and brittle or mishandling them upon assembly and will leak oil out of the head and into that spark plug well and eventually out that hole........
If you are losing coolant (assuming that is why you post up your recovery tank photo) is it coming from that same area or someplace else?
if coolant is coming out that hole then you have head gasket issues (and likely would also need to do something about decking the head and possibly the cylinders as well
Seems to be more like oil coming out not saying it's not coolant its not alot but hard to say when in taking it around the block. Looking in to going a some waht rebuild kit for it. If the miles are right one it has 40+ thousands miles on it.
Touch the fluid with your finger tip and taste it, Only a tiny amount needed, If it's Bitter or Sweat tasting it's Coolant.
My go to test for any suspect coolant leak in fact I used it today on a KTM 790 and it was Coolant leaking