You might be able to get away with using one of these, I’ve had luck in the past on a Subaru…

https://www.amazon.com/Dorman-Help-10691-Radiator-Overflow/dp/B000CO8ZT2

Looks like the radiator is cracked or has a tiny hole that’s spraying coolant everywhere when it’s hot and up to pressure. I would wait for it to cool, top off the coolant and then get it hot again to pressurize the system and look to see if you can tell where it’s coming from. BE VERY CAREFUL obviously using this method could spray hot coolant in your direction.

Valve cover gasket/spark plug tube seals are leaking. This is what’s causing your misfire issues as oil on the coils and plugs is no good. Replace the gasket and spark plugs, clean the coils well and all should be good!