No, don't know what those two screws are for but it's not a Sterling production gun and obviously nothing to do with zeroing either. I would imagine that that they are retainers for the foresight housing. The locator being the larger 4BA(?) allen bolt seen at the 6 o'clock position. In real life the 'retainers' are not required because the muzzle cap is pulled rearwards against the rods and clamps the foresight block in place. The 'locator' and the steel stud in the brass front barrel centraliser keeps everything aligned. Another bit of useless Enfield sort-of related info

If anyone has got one of these guns that they use regularly then I'd suggest that they replace the awful rods and muzzle screws with stainless steel. The originals were a total PITA.