*I have heard this quoted multiple times “Rishonim are malachim”.
Either you heard wrong, misunderstood, or hang out with fools. Nobody says Rishonim were malachim. Even the expression “Im Rishonim k’malachim” is not referring specifically to talmidei chachamim following the Geonim, it’s an expression which refers to the relative greatness of previous generations. On that we do have a mesorah, so yes, we do tread very carefully when dealing with the words of the Rishonim.