It could be either, my last CE flight from MAD on a 767 was longhaul though CE also went to the WTP cabin. More usually there is a set of 767s with shorthaul seating. Up to row 17 they have increased leg room. CE may extend that far back, particularly for MAD, but often doesn't so in ET you want to be near the front. Statistically it is more likely to be shorthaul, but the MMB seating map will change if/when a longhaul is put on your service, and you can also tell via Expertflyer (e.g. by setting a seating alert).