I've been having a tough time with them, too! This afternoon I just sat down and watched TV while having the Switch in my lap to wait for balloons on the beach. They tend to spawn every 10 minutes. I finally managed to find two today. Good luck!
I play for 8 hours a day and have hit so many solid balloons but tend to get bells or iron...I did get the cherry blossom walls and didn't realize it was new (I have the sakura walls and floors and didn't realize there were also cherry blossom walls and floors and sold the recipe ) But I am still missing several recipes.
I'm not sure why but balloon always come to me even when I only play an hour or two. Got 2 diy yesterday (final one) in just under an hour of playing. I don't even farm for these things, I just happen to hear a balloon while I'm chopping my trees and shoot it and boom DIY!