Feedback on our Itinerary?

Two full days (or even 2.5 days) is probably adequate for Dubrovnik because it's very compact, but you can use the extra days to take side trips (Montanegro, Korcula, etc. are very good bets). I went to Korcula from Split due to timing issues but I think it's as accessible from Dubrovnik. You might also consider seeing Trogir which is very close to Split (it's accessible via bus).

I liked Rovinj a lot, but I urge you to spend a night at Plitvice (or nearby) so you can enter the park early the next morning before the crowding becomes insane. It's such a lovely place, you want to see it at its best.

Check online info on cruise ship docking schedules at Dubrovnik and Kotor to plan your time in the Dubrovnik area. Avoiding the worst days can make your experience there much more pleasant. You may have more time than you need in Dubrovnik, so perhaps consider Mostar in Bosnia or additional areas in Montnegro.

Inland Istria is very interesting and best visited by car. Perhaps you'll have time to see one or two of the small towns on your way from Bled to Rovinj. I liked both Groznjan and Motovun.

It's pity you don't have time for Ljubljana, which is a very nice small city, but there's always another place to visit when you've run out of time.

Zagreb has quite a lot of museums, so check for info online to see whether any are appealing. The Museum of Naive Art is very good, and it's small enough that it doesn't take long to visit.

I agree, two full days are enough for Dubrovnik, the rest can be spent doing day trips or reallocating it somewhere else - perhaps to another night in Bled. As things stand with regards to Bled, you'll be arriving there in the late afternoon, spending the night, exploring the next day until the mid-afternoon and then departing for Rovinj - not ideal. It makes more sense to spend a second night in Bled to have a full day there, giving you enough time to see Bled and the surrounding sights. Reallocating one of the Dubrovnik days, you can then use it for the drive to Rovinj, stopping in Ljubljana and one of the Istrian hilltop towns along the way.

I agree with Dejan -

1. Add a day from Dubrovnik to Lake Bled - we stayed 3 nights there in May and loved all of the hiking and biking. At least give yourself 2 nights so you have one day to explore.

2. Add in a night for Plitvice from Hvar. We were told to spend the night in Plitvice and get up early to do the hikes. We were in the park by 8 and out by 2 and off to Split. We loved it ! You have 4 nights in Hvar - we stayed 3 nights and felt it was relaxing.