Absolutely - I've never pretended to know everything or be so completely polyglottic that I can immediately and thoroughly interpret a codebase. I do, however, understand the "logic between sdc and shadow", and have limited my observations solely to Shadow (as described by the whitepaper).

"Zero-knowledge proofs" are a special type of cryptographic proof that allow you to verify something, prima facie, without knowing all of the details thereof as part of the proof. It is a special class of proofs, and doesn't refer to a unit of measure (i.e. tokens). Our current cryptographic body of knowledge is easily able to identify (cryptographic) zero-knowledge proofs with respect to transaction verification in cryptocurrencies, and Zerocoin / Zerocash (along with their failings from a verification speed / size / trusted accumulator perspective) are among the leading implementations thereof. At this point the "unknown" nature of subtle flaws in those cryptocurrencies make them unattractive for those of us more focused on the "now" than the "then".