There’s a lot of potential to impact crowds & turn it into a high crowd time, even without school being out. There’s Food & Wine and Pixar Fest which does include the return of Paint the Night to DCA, but there’s also, Passholder non-blockouts, SoCal resident discount tickets (2 & 3 day multi-tickets), and unannounced school groups usually middle school & highs school choirs, bands, teams, etc. that come for a spring trip outside of Spring Break.
Last year when there was the return of favorites Main Street Electrical Parade and Remember Dreams Come True Fireworks combined with the SoCal resident discounted tickets (only 3 day option), there were a lot of unexpectedly busy days. I would look at the crowd calender actuals from last year for the same week you’re planning on, to give you a better idea of what to expect this year.
That said, the weather in Spring in SoCal is just about as blissfully perfect as it can get and even when busy you can see & do so much by getting to the park early for rope drop, using MaxPass and having an agenda or plan of what you want to see & do.