By that logic knowing Spanish, Portuguese and Italian wouldn't make you trilingual since they're all related with different "key words, library function names", etc. I mean vocabularies and small grammar rules.
Taking myself as an example, I learned French in junior high (between the ages of 12-14), never lived in a French speaking country, and never learned a word of Spanish - and yet, I can read and understand simple Spanish. If I upgraded that to full-spanish, I wouldn't count it as a "whole new language".
(p.s. my mother tongue is neither English, nor is it Latin, Germanic or anything else that might have any remote connection to English, French or Spanish)