You're guessing though on a number of issues where the information is actually known. I briefly covered the circumstances of that Philippine AF P-26 claim of a Zero downed, Dec 23 1941, above already, but to expand and reiterate:I am going to hazard a few guesses in regard to the issue at hand.
1. i am guessing firstly that the pilots of these planes were not filipino, but Americans, being paid by the filipinos.
2. Secondly, nearly every Japanese plane in 1941-42 were reported as Zeroes. It could just as easily be Nates, or perhaps even Claudes. The Japanese had captured advance air bases very early, so as to allow their shorter ranged fighters the ability to participate in the battle.
3. Thirdly, it may well have been Zeroes, but if those zeroes were operating from Formosa,
1. Definitely Filipino pilots, the pilot credited with that victory was Lt. Jose Kare.
2. True, there was a tendency in popular accounts to label all Japanese fighters Zeroes, but less true wrt to actual pilot reports at the time, although the lack of a uniform designation system caused confusion. That was the reason for the 'nickname' system, which appeared later. On December 23 there were Army Type 97's ('Nate') operating from bases in northern Luzon, and Navy Zero's operating from Legaspi in southern Luzon, the claim was in southern Luzon. Navy Type 96's ('Claude') conducted the first air attack on the Philippines against Davao from the carrier Ryujo Dec 8 but were not opposed, saw no air combat action in the PI.
3. Again these would have been Tainan Air Group Zeroes based at Legaspi.
However, as noted above the Tainan suffered no losses December 23. Shores et al "Bloody Shambles" mistakenly 'possibly' matches this claim to the Tainan AG's loss on the 24th (PO1C Toshio Kikuchi) stating that otherwise no Allied claims would explain it, however there was in fact a claim by US P-35's the 24th in circumstances matching the Zero loss (v. one P-35 so badly damaged it was wrecked on landing). So there were apparently no victories over Zeroes by P-26's. Again as mentioned previously traditional Allied accounts have also claimed 2 Zeroes downed by P-26's Dec 10; that combat was v the 3rd Air Group (the Zeroes were flying from Formosa at that point) but it suffered no losses in fact. The website Evang referenced modifies the Filipino claims to be in line with the two-sided accounts in "Bloody Shambles", which is a laudable general principle for official histories, way too many easily discountable one sided claims from WWII are still stubbornly quoted as if facts. But again in this case it's an unusual error in that book, no known Zero loss corresponds to that claim, and the records for JNAF fighter operations in the Philippines in 1941 are relatively detailed and apparently fairly complete (those of JAAF fighter ops in PI 1941-42 are much less complete, but again it's not likely that plane was a Type 97 given the location).
Joe