i am planning to travel for 24 nights to china starting from guilin.

From Yangshuo, there is no train to Kunming, you need to go to GL to catch the train. But as I know, there are only two trains between GL and Kunming, k393 using about 24 hours and K181 using 19 hours. So for this trip, it is suggested to take a flight.
The night train from Kunming to Dali, so you can take the night trains. Then to Shangri-la and Lijiang, you need to use the local buses.
From Lijiang, it is hard to get to Leshan directly, so you need to reach Chengdu first and then take buses to Leshan.
To reach Xian, you still need to take the trains from Chengdu. From Xian to Beijing, the night train exist, so you can choose to take.

thanks
Do you think it could be too many things crammed into this relative short time?

For the places you are visiting, here is my suggestion on an itinerary:

GL - Yangshuo - GL (easy for transportation)- Kunming - Dali - Lijiang - Shangri-la (there is a direct plane to Chengdu) - Chengdu (although a transfer place, it is also worth a visit) - Leshan (then Chengdu for transfer again) - Xian - Beijing

If you will have a DIY travel, it will be a little hectic in Yunan province. Therefore, it is best to join a tour for Yunnan province travel (KM, Dali, Lijiang and Shangri-la).