It could be a dialectal word from Northern Spain, perhaps galician or asturian; the headscarf and earrings point to Asturias (the crosses are like the one on their flag), and the name "Carmina" sounds to me like a regular asturian name, "Carmiña" in Galicia.
Although asturians use "in/ines" more than "ino", so I'm not sure: "Guapín/Guapines", "Chiquín/Chiquines", "Chatín/Chatines".
I understand your confusion if you're not a native, but as a Mexican, I don't think anyone fluent in Spanish is going even bat an eye at "guapinos" given context such as this.
It's perfectly organic despite not being necessarily correct.
