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jesus christ what a mess of a thread.
coolant has a less cooling ability than water does. switching to coolant won't increase your cooling capacity.
if you had a leak in the system it would leak all the time. you don't have a leak in the system.
if you had air in the system, you wouldn't have water spewing everywhere, the system would be low, eventually the air would work its way into the reservoir and during cooling cycles the system will pull fluid to replace it. if there's too much air and the system is never able to fully pressurize, the cap will never open so you'll just overheat without any fluid spilling from the reservoir overflow.
you have what's almost certainly a bad rad cap, or some junk in the rad cap seal that's allowing the system to push fluid into the reservoir.
your cooling system is pressurized, this increases the boiling point of the fluid within it. the rad cap has a spring in it that allows fluid to migrate into the reservoir when the system tries to over pressure. so when the bike is hot, it's totally normal for the level in the reservoir to increase.
as the system cools off, there is a check valve in the cap that allows fluid in the reservoir to migrate back into the radiator.
if you have a bad cap spring, or a bad check in the cap, or a piece of crud in the cap seal, the system is never able to pressurize. when this happens, the thermal expansion of the fluid due to temperature forces it easily into the reservoir, overflowing it.
to put it briefly, check your rad cap.