True that Mondia was ONE of the marques that pointed the stay ends like this, but there were others, too. It's a style seen on some Austrian frames, perhaps other Swiss too but Mondia is the best-known. That said I don't think this has much else "Swiss" about it, the Oscar Egg lugs (and I do think these may be that brand plus the BB shell and forkcrown look "right") were favored by Brit builders as well as some Continental marques. Stuff of this ('40s to '50s) era is beyond me but bet this turns out to be something good. We need somebody with older European bike knowledge to chime in, maybe juvela for starters.