That "tang without going soft" is the dream. My buddy tried fermenting radishes last month and totally messed it up, left them in a crazy warm spot for like a week. They turned into mush soup, it was so bad. He saw @burns.brian talking about the three day room temp rule and tried again, nailed it the second time. His whole kitchen smelled funky but man, the crunch was perfect.
Nice. I had the same worry about mush. My trick was using a cooler spot in my kitchen, like the bottom cabinet. Three days there gave me that sharp bite but they stayed super crisp. Almost like a spicy pickle. That crunch is everything.