Is there a way to obtain Island beautifications from the past, such as, the 1st sunrise shallows?

No, not at this time. But who knows what the future may hold. At one time the Grand Prizes from the seasonal sets were exclusive, never to return, but now they return in the Limited Edition store.

Past Seasonal Set Items are frequently offered in events (Detectives Needed, Fairground Fortune, Sweep the Board), Limited Edition shop (tap the cash register and the watch), and the Deja Vu tokens shop. To see what items you might want, you can go to Regis' June's Journey Albums and look under Seasonal Sets, Event Rewards, and Limited Time Offers. To see what items will soon be offered, you can go to junesjourneyguide.com/calendar.