Stew
Sedans Rule!
I feel like scot might be on to something. If you get a sleeve to fit the 14mm mounting hole on the bracket made for a 12mm bolt you could still use the 12mm bolt. Though you could be correct in the reverse thinking bit as well.
No because the threads are in the BRACKET, not the spindle mounting hole. That sleeve would work to go back to stock though. You cannot use the Sonic 12mm bolts in the Encore 14mm threaded holes.
Brackets came in today, I've got everything. Going out to do some drilling and put the Encore brakes on, if all goes according to plan I'll report back later with details!