you completed that ghastly course!
I did!
What I learned from it wasn't colour theory as such; I already knew about the colour wheel, lights and darks, proportions etc. What did become very apparant from the experience is that whilst I very much like bright colours they do need to be balanced by neutrals, (greys, beiges, black, white). Those are missing from that quilt. I also like pattern but the different blocks are such a hotch-potch.
It's the same when putting an outfit together. You might choose a brightly coloured, patterned top but then add plain black trousers and pick one of the colours for a scarf. You wouldn't (I hope!
) go for a pink and green floral print top, blue and red checked trousers and then add a turquoise jacket. Bright colours can be the dominant part ie a dress, but the accessories need to be plainer and subtle.
Wrenkins, use your sludgy, cowpat colours with bright contrasting colours. Maybe choose one of the many star blocks and use bright colours for the stars and the dull, subtle ones for the background pieces. Use lots of different subtle colours scattered randomly through the quilt, but keep them broadly in the same colour family, and the bright colours will sing out. Go for it!