Hello: I apologize. I did not mean to imply that one Posek raised a question about all of them. My point was you can find at least one Posek who would not make Hamotzi on each of the 5 grains. There are many by oats nowadays. I do not recall who said what, but if I am not mistaken Rav Unterman and Rav Hertzog had the issues with spelt and rye. I do not recall who raised questions about wheat and barley but I remember that it was more than just historians.
Regardless, I was just saying that if you would assume that the poster’s Sfek Sfeka above should work. I am not Makpid on Yoshon for other reasons that I mentioned earlier in this thread. And your questions are exactly why I wrote my aforementioned “Purim halachah” years ago. As I also said above, there is nothing wrong with assuming that the 5 grains are really the five grains and that I would never tell someone who cannot tolerate gluten that they cannot make Hamotzi and Bentsch on oats, which is the most questionable of the 5.