I think it's generally very hard to follow texts that use a lot of distinctions that one doesn't use.

Metaphor seems to be a term that we all know Condensation, Metonymy and Displacement not so much.

After reading this text we can ask: "Why is metonymy found at the side of the signifier but not at the side of the signified?" "Why is metaphor found at the side of the signified but not at the side of the signifier?"

I'm not sure what kind of answer a person trained in Semotics would give but there might be meaningful answers.