“No, the point of understanding the fallacy is realizing that the existence of Q does not necessarily support P. It only appears to because the believer is engaging in fallacy.”
—If P claims Q, and Q is found to be true, then P IS supported. How else is P to be supported? How else does one investigate a theory or idea than to test whether the predictions (Qs) of the theory/idea/claim (P) are true or not? But one has to remember that ‘supported’ doesn’t mean ‘proven’ – that is the point of the fallacy. P can be supported by Q, but not proven. One doesn’t need to rule out every other possible explanation of Q other than P for P to be merely “supported”. Whenever Q is found to be true, P is supported and the theory lives another day, but it is not proven since there are always other explanations for Q other than P. As long as one remembers that, they are not committing the fallacy.
“It is not necessary for evolution to be claimed to be a logical certainty for the fallacy to operate.”
—The fallacy states: “If P, then Q. Q is true. Therefore P.”
In the language of logic “therefore P” means “a logical certainty” or “absolutely proven”, not merely “supported”.
You are still a little confused about Q. Q is not 'true' or 'false', Q is observed or not-observed. Q is not an explanation that can be true or false. P is the explanation and can be either true or false.
"How else is P to be supported?"
P is supported by eliminating all alternatives. Otherwise you are simply engaging in logical fallacy. That's the point.
"How else does one investigate a theory or idea than to test whether the predictions (Qs) of the theory/idea/claim (P) are true or not?"
What you are beginning to realize are the limits of science because theories are dependent on logical fallacy. This is why theories are constantly overturned and is an inherent weakness of science. If your theory is philosophical (like evolution) you cannot claim that it is scientific because huge portions of it are assumed, untestable and unfalsifiable. If your theory is methodological (like superconductivity) you may claim that it is scientific but it is still subject to being thrown out because not-Q can be observed at any time.
In sum, methodological theories can be overturned at any time and philosophical theories are unfalsifiable.
"—The fallacy states: “If P, then Q. Q is true. Therefore P.” In the language of logic “therefore P” means “a logical certainty” or “absolutely proven”, not merely “supported”."
It is not a 'logical certainty' or 'absolutely proven' that P is supported. It may appear that P is supported but alternatives to P may be supported as well. P may very well be false and Q may not have supported a false theory at all. That's the fallacy.