I _tried_ to give a definition to embeddings on page 11, but maybe that's not the most intuitive? Lmk! feel free to DM
Relevancy is dependent on and relative to a specific task or interest. "Related to" or "associated" might be a better choice, since parts of a text can be statistically associated with each other.
While I feel that you are accurately conveying the terminology in the field I personally feel that terminology overstates things. For example, the notion that words closer in meaning are generally closer in latent space could be more accurately stated as "words closer in latent space are often used in similar ways."
I think this comes down to meaning being largely determined by a person's individual interpretation at a given point in time, similar to the arbitrariness of relevancy.