Hi Kate,
The way I see it is, when a plant of any kind is moved from one place to another it sometimes takes a little time to settle in, not just to acclimatize but to 'sunatize' too.
Most Acers, with the possible exeption of some of the more delicate Japanese varieties, should be okay in sun or shade and if you are now sure it is scorch and not diseased, then I would think the problem is only short-term and will eventually sort itself out.
I feel I must say that spraying with water in bright sunshine is likely to make the problem worse, as the droplets of water on the leaves can act like tiny magnifying glasses and amplify the suns rays.
To summerise, If your happy with where it is, then I think given time it will addapt and out-grow these teething problems. Good Luck.