Getting back to the OP’s original post - can‘t tell if that’s coolant or if its the rear crossover from the picture. On the SCV6, you can’t see it the crossover from that angle, but maybe on the V8 you can. If I had to guess, that looks like the diverter or t-stat that sticks up off the crossover. Usually the crossover will not leak in that spot, but its possible.
In any case, if you are leaking a pint every two weeks, you should be able to find residue someplace (and you should smell it from the engine compartment after a longish drive). If it’s the rear crossover, you should find it by dropping the skidplate - look on the top of the skid or maybe the top of the transmission. The other place to check carefully is down in the valley of the engine from the front. You should be able to peek down the side of the oil filter and see if there is any residue. Also, look around the waterpump - behind and below. A borescope is really helpful for this job.
If you can’t find a leak, change out your reservoir cap - you might be boiling some off due to a bad cap, but doubtful you’d be boiling that much off.
Another possibility is the heater core (you’d probably smell it in the cabin), or the heater lines that go back to the rear heater. They start sort of under the battery box, and continue along the bottom of the passenger side of the car up into the rear wheel well.