Sam2, Rabbi Chaim Jachter used to have a whole bunch of essays posted on his website which were taken down now that they are in his book “Grey matter”. I believe, iirc, that the answer was that that was a confirmed site, where they were saying “moshe emes vesoraso emes ve’anachnu badaim”. Any other archaelogical proof isn’t guaranteed. Some say they found the alter of Joshua, so you can measure it and determine the ama. But other archaeologists say it was just a tower. They found a piece of cloth which was based on the murex trunculus dye and it was a darker color. So this means the murex was techeiles, and it was darker? They didn’t find tzitzis. Finally, there is a gemara in bava metzia where the beis din shel maala paskened tamei and Hashem paskened tahor. Rambam paskens against Hashem. the meforshim analyze it and say emes is determined by chachamim. I saw it quoted here in the CR years ago, forgot exactly where.
As for oats as mezonos (machlokes rashi and rambam, yehuda felix backs rambam based on his research), my own rav is meikel for a bracha but says you shouldn’t eat oat matzos on pesach unless you have no choice, as we should be chosheish for the rambam. Yehuda Felix does not factor into it. Rav Shachter makes a ha’adama on it.