The Warners are designed to know 'everything'. They never needed to relearn history or catch up. The audience would get some lore dumps every couple of episodes.
Watch episode 65, which is the 65th Anniversary of the Warners episode. It's the one episode that goes deep into the most canon lore of the Warners. Explains that the kids were never permanently locked up.
Episode 26 also features small segments from fictional Hollywood people who go on about how involved the Warners were during the 30's before they were locked up.
Episode 91 has some minor additional lore dump, but it's mostly used to make fun of the limited animation scene after UPA ended.