I now know that in Italian I should say 'mi piacciono' to convey my liking of things (plural), e.g "mi piacciono i libri" means "I like books", as opposed to singular 'mi piace il libro' (I like the book).

When I refer to likes of multiple people, e.g. "we like this book", I should use "ci piace il libro". Plural people speaking about liking plural books would be "ci piacciono i libri".

One of my goals for 2026 is to reach level B1 in Italian language.

Yeah, somehow Latin-based languages prefer the opposite direction of the activity of liking, so it's better to formulate it initially as: this book appeals to me, those books appeal to him, ...

Opposite as in: "You borrow me X. I owe you X."