It's good to see that you've finaly posted one of your job ideas ^.^ I've seen you posting in other job idea threads and after seeing your signature, I always wondered what you'd come up with
I'll admit that when I first read the excel sheet, I was quite confused with what you wanted us to do. However after a while of scrolling up and down the list of spells and abilities and imagining playing it, I think I get roughly what you're supposed to do. It seems like quite an interesting job. =)

Just a few little questions atm. I was wondering what you thought to adding an instant cast spell or maybe making the 3 primary colour spells 1.5s cast time? It's mainly for using the sketches really as they're every ~20-30s and the only instant cast spell you have is the DOT. It just doesn't sound like they'll sync up enough so that you can refresh the DOT when you need to sketch (i.e. you can't proc the GCD so that you can use sketch in the oGCD).
I was also wondering about Colour Splash. It seems quite powerful but I was more wondering about maybe lowering the tank buff to 10% to bring it in line with the total % buff each role with receive in the party. Basically in 4 man content, the tank and healer would get 10% to their jobs each and the DPS would collectively get 10%. In 8 man content, tanks, healers and DPS would collectively get 20% to help with their defenses, healing and damage respectively (this point is also partly my OCD wanting them to be the same ).
My last one was about the lvls you learn Ebony and Ivory. I was thinking that maybe they should be learnt at different lvls because you don't usually learn more than one spell or ability at the same time. This one is also partly personal preference. =)

Overall though, this sounds like a really interesting idea and I'd very much like to try it out! I was initially worried that you wouldn't use some of the sketches once you lvled up (see Titan-egi T.T ) but based on the recast timers you appear to have to use them all which is awesome ^.^ Obviously this doesn't apply in fights with significant down time but what can you do? Big thumbs up from me =D