Route Feedback/Recommendations: Rotterdam – Ljubljana

I'm planning a cycle tour from Rotterdam, leaving in late April!

I've tried to construct a route which includes some destinations that I'd like to see, as well as cycle routes which are beautiful, fairly easy to navigate and not too hardcore (hence lots of rivers, EV paths and mostly avoiding the Alps).

This is my first tour, although I do have day-riding experience. I'll be doing a couple of weekend trips beforehand to test my equipment and get my body accustomed to the strain.

I'm looking for some feedback or recommendations: is there anything worth going out of my way for, any alternative routes that would be better, or anything I should avoid? Also any general advice for the trip!

Particularly the section between Budapest and Ljubljana I'm unsure about. I've just stuck the EV14 and EV9 routes together but I can't find too much information about those sections, and I've read it might be difficult to navigate there.