If I had to venture a guess, I'd say it's a lower-tier European bike. If the BB shell wasn't 68mm I'd say it was Italian. That's where I usually see the Coronado cranks. (BTW, there are various Coronado models, so whether it's a model name or a sub-brand remains to be debated. Anyway, they were made by Thun).

On another note: I really like that bike. The frame looks like it might be a nice rider, and the parts selection is just about the best you could get if you were on a budget. The Coronado cranks I have are very light and the Shimano Altus derailleurs function better than any Campagnolo stuff from the era.

I agree with T-Mar on the dating: late seventies. Here's my Legnano from that era, built in a similar vein: