Oh this sounds like me. I ALWAYS make-up new languages. I just love it for some reason. I can only fluently speak in one called "Adibikicyan" fluently. I like to annoy people sometimes by telling them things in Adibikicyan that they can't understand.
It's basically taking letters, turning them into numbers, and then back into different letters. "Ayibidi" is my name (Lexi) in Adibikicyan. If you take out the first 2 i's that are just there to make it pronouncable (When I write it on paper they have little marks of them so you can tell) the numbers (As in a=1, b=2...etc) are 125249 in both of them. That's basically how it works.I made it up long before I knew anything about syn, and it doesn't really have anything to do with colors. But I can pick up on foreign languages pretty easily. Memorizing with colors and stuff.