Hey, sounds like a reasonable itinerary for relaxing and sightseeing.

• Is this still too much movement with a toddler, or reasonable for 13–14 days? Since you have a toddler I would say to move as little as possible, also these destinations you will be visiting with a ferry or you will be renting a car ?

• Is Korčula + Hvar redundant, or do they feel distinct enough? Islands are great for relaxing and exploring, if you plan on sunbathing and exploring half a day you will have about 3 -4 days of things to see in a more slower pace, which would be great due to the toddler. Korcula is better for kids as has sandy beaches.

Hvar or Korcula: Which island is better for you?

• Any strong opinions on Krka NP with a stroller or baby carrier?

I would not advise due to many steps, parts of Krka are flat and easy with a stroller but then you come to certain parts that are not designed for a stroller, would advise a child carrier

• Anything you’d swap out or simplify?

I would add an extra day to an island instead of Split. Also if you plan on spending alot of time on the beach, Makarska is popular for families due to large amounts of pebble beaches, but in my opinion Korcula with its sandy beaches is a bigger plus, also you can go visit Mljet national park or an island with deers etc.

Korcula guide, an island not to miss in Croatia

Best Day Trips from Korcula with a boat

Here are few guides for other mentioned locations:

Beaches on Hvar Island: Best Beaches Close to Hvar Town

Top 5 Day trips from Dubrovnik -- Dubrovnik 3-Day Itinerary : What to see and do

Top 5 Beaches in Split

2 Days in Split what to do and see Itinerary

8 BEST DAY Trips from Split (Guide) By Bus or Car