>>106"Es difícil saber cuáles son acertadas(?) y cuáles están obsoletas".
I don't get what you meant by accurate. Accurate means correct/certain.
Do you mean accurate with regards to knowing which metaphors are correct or suitable in a given context? Or does it have to do with discerning an actual metaphor from a bogus one?
Obsoleto strikes me as odd in that context (in Spanish), given that it tends to be associated with technology/the way of doing something.
I'd use "cuáles cayeron en desuso" (which ones have fallen into disuse) instead, which lends itself better to this context.
Furthermore, the rule of thumb goes that the verb ser refers to the nature of something; its inherent qualities, and estar refers to the state something is in.
Fulana está fea -> Fulana is ugly (you don't like something about Fulana's current look)
Fulana camisa es fea -> Fulana is ugly (Being ugly is a trait of hers)