So, let's see who certified what:
View attachment 132899
The certification was by Baylor, NOT BY THE FAA. Critical difference there. Show me in that document where the FAA certified the O-235s and O-540s to run on ethanol.
https://afdc.energy.gov/files/pdfs/2896.pdf
Sure. The Baylor studies from the '90s. If the FAA had certified the O-235 and O-540 for ethanol, the TCDS would show it by now. The TCDS is the authoritative document published by the FAA for such things. Let's have a look at the O-235's TCDS:
View attachment 132900
Hm. See when it was last revised? January 31, 2020. That's at least 27 years after the Baylor studies. If the engine was indeed certified for use on ethanol, the TCDS would have shown that a long time ago.
The O-540 TCDS:
View attachment 132901
April 20, 2013, 20 years after the Baylor studies, and there is no certification shown for use on ethanol.
If you use fuels other than the engine was certified for, or STC'd for, you are in big trouble when it quits or when some FAA inspector discovers it. Mogas STCs specifically prohibit the use of gasolines containing ethanol:
View attachment 132903
And yes, ethanol qualifies as an alcohol.