Where are the water jacket core plugs located?

There are 2 core plugs on that engine, and both are on the opposite side of the engine than the water pump. If the leak is on the same side as the pump, I would suspect the inlet pipe that goes into the pump, either a bad O-ring or the pipe itself is cracked.

The inlet pipe is dry, and the coolant "seems" to originate on the right face of the engine. Spatter/kickback/spray is making the origin difficult to pin down. No coolant present in the oil (checked by drip pan, no separation or discoloration in the sample, checked by dipstick, no foaming or discoloration). There does seem to be a "clean" area on the engine on the right face that is less grimy/normal grease is thinner with possible coolant. It is possible that is due to kickup of coolant.

Appreciate the diagram! Thank you.

To find a stubborn leak there are a few tricks. One is to add some UV dye to the coolant. Then clean off as much of the engine as you can cold. Now start it and look for the dye as it warms up. With the amount you are losing it should show up rather fast. Another is to dust the engine with something like baby powder after adding the dye. The powder absorbs the dye and may leave a trail with the leak at the starting point. If you wanted to test it under pressure without starting the engine you could get a cooling system pressure tester from a parts store as a loaner tool. Then use that tool on the cold engine. Coolant shouldn't spray that way.

https://www.2carpros.com/articles/radiator-pressure-test

Thanks! Added UV dye this evening.

Now you just need to find the glow! I normally add it, then run the engine a bit so it mixes, then grab the UV light and go looking in either a darkened bay or at night as it really makes the dye stand out if there is no bright light to hide it.