Even a clean Mao will get lower GOE and lower PCS than a clean Kostner and a clean Kim. Whether it would be enough to compensate the base value difference I am not sure, but you seem to be under the impression a clean Mao would easily match Kostner and Kim in GOE and PCS, and all evidence is this is not the case. Her jumps are much lower quality even landed than theirs are and rightfully get lower GOE, and even some of her other elements often are lower, and her PCS have consistently been lower than Kim since 2009 and Kostner since 2011 now, regardles of performance (aka when they make more mistakes or glaring mistakes than she does, they are higher).
Your basing scores on an event in Japan is flawed since Mao always scores higher in Japan than she will elsewhere for comparable mistakes. A hypothetical of Mao averaging 9.5s in PCS is also flawed as this will not happen (especialy outside of Japan).
I think Mao scored well at 4CC because it was one of the last competitions of the season, and she has been progressively improving throughout the season. Yes, her SP score at Worlds was bad because she messed up, but she did score her season's best FP score at Worlds, so it was not because the competition was held in Japan that her SP score was high but because her skating improved.
The average 9.5 PCS was mentioned in context of Yuna's hypothetical maximum short score, which would be 77. Mao scored 74.49 with PCS average of 8.466.
Regarding GOEs, yes, one cannot predict that Mao would match Yuna's and Caro's GOEs even on table, but it is also worth mentioning that there were some jump elements where Mao's GOEs basically matched Yuna and Caro at Worlds: namely salchow and 2A+3T. With spins on GOEs, Mao is a bit hit and miss, but it is my understanding that Mao cut back on practicing her spins this season, and so it is realistic to expect her to get equivalent GOEs on spins next season. Also, Mao will get better or equal GOEs on steps and spiral sequence than these two.
So Mao so far has failed to get GOEs on three elements: 3axel, 3flip and 3lutz. So it is not as if Mao has to improve on many, many elements from here to Sochi. Just these three elements, and she has been improving steadily so it is reasonable to predict that she will make some improvements from here to Sochi on these elements. Of course, we cannot expect Mao's GOEs to be better than Yuna's and Caro's toe jumps, but if she can just stop under-rotating them, we can expect her to get at least +1 GOEs, which is feasible.
Regarding PCS, comparing PCS of Worlds FP, Mao's average was 8.55, Caro's 8.8 and Yuna's 9.2. Mao was very hesitant in the first minute and had under-rotations and wrong edge, so if she were to skate fairly clean from the beginning of next season, I think her PCS will go up.
Yuna's maximum score I think ought to be 77 for SP and 150 for FP, meaning we are looking for a skater who can score above 227. Combining Mao's best scores this season, she scored 208. This 208 precludes a 3-3 in both short and long and includes a double-footed 3axel, two under-rotation calls, one wrong edge call, a loop without the GOE that she is capable of and an inclusion of a 2loop instead of a 3loop. If she can have 3-3 in both short and long, do a clean 3axel in both short and long, get rid of her under-rotations calls, and put in two 3loops instead of one, I think she can score another 20 points.
Well... it is a long shot, but it's not impossible. If Mao can bring up the quality of her 3axel, 3flip and hopefully 3lutz during the off season, she has a chance.
