Lily_Vn“Can you explain the difference between ''couldn't see
with can't have seen'' ?
”
Can't have seen her: this expresses deduction about a fact.
Luise was in Palma, so she was not in the library, so it was impossible for you to see her in the library = you can't have seen her.
Couldn't see her: it might work in other contexts, such as: She was very short, so I couldn't see her (= I was unable to see her) as she was surrounded by the crowd.