yankel berel, thanks for correcting my sloppy reference to knowing all poskim instead of being able to navigate them (Hashem somehow wanted me to acknowledge this at least twice as the first one did not show up). Not relying on my own reading, I searched how others understand this Ramo, and it seems that it is understood as a pretty high requirement. also, someone mentions that Ramo brings this solely as a criterion for someone not to pay taxes in a community, while it is Hazon Ish who is elevating the criterion to a general definition of a Talmid Chacham.
So, I would be interested in seeing an exam that verifies learning qualities according to Ramo’s definition.
But maybe it is all in vain. I see in R Twersky a discussion about who is a chossid (in my eyes, a mailah higher than T’Ch):
A: the one who wants to be a chossid
Q: but who does NOT want to be a chossid!?
A: the one who thinks he already is a chossid.