The Avi Ezra clearly said he knew the gemara; it is not for people in our time and level to make definitive statements about rishonim; we would disintegrate from the kedushah of their Torah if we were to meet them.
Rav Chaim volozhiner wrote that the Gra once slept and upon awakening, told him that while asleep, he had learned 50,000 perushim in one pasuk, and was able to understand the meaning of every eiver of every living thing with the first of them.
And the Gaon was not as big as the early rishonim.
The maharshal didn’t say he was not familiar with basic gemara; such a person never would rise to any sort of rank in the Torah world – the simple baalebatim in litvishe towns knew shas and shulchan aruch… it’s preposterous. What the maharshal wrote was that he was not a basl talmud; he wasn’t outstanding, a master, of the gemara; but that’s for him to say. Would you likewise take as given the litany of insults the raavad wrote of the rambam? We’re not permitted to speak that way; it would be malig al divrei chachamim, which is a capital offense. Not that that seems to matter much to you in the pursuit of “truth”
You must have had zero chinuch in how we approach rishonim, achronim, and today’s Torah leaders; either that, or you choose to ignore that chinuch and draw your own conclusions.