Multi Asian Country Itinerary

I am looking to make an itinerary for a multi country trip to Asia. The countries would be Malaysia, Cambodia, Taiwan and China in roughly 3 weeks around March/April 2024.

For the itinerary itself, I’m thinking something like this: - Malaysia, 2 days in Kuala Lumpur - 1 travel day - Cambodia, 3 days in Siem Reap - 1 travel day - Taiwan, 3 days in Taipei - Taiwan, Day trip to Juifen and Shifen from Taipei - Taiwan, 2 days in Taichung City. - 1 travel day, from Taipei - China, 2 days in Shanghai - 1 travel day - China, 3 days in Beijing or 2 days in Beijing

I’m aware the countries are not necessarily super close to each other or that having more time in each country would be better, but overall I’m happy to hop countries in a short time as long as I get to see this 4 in this amount of time.

Any ideas on improvements or optimisations for this itinerary are more than welcome.