if i want to travel area guangzhou/guilin during mid of feb2020 is possible with train/buses?

Yes, generally speaking, the public transportation will operate during that period of time. Don't worry.

Public transport is always crowded during the Spring Festival; make sure you book your tickets a month prior;

Don't worry, the most rush time for transportation is 3~5 days before Spring festival and also 3~5 days after Spring festival, because those time people need to go back home town and get back to living place. And public transportation never stop operation during that time. The best way to travel in China is by train, chip and comfortable. Just during Spring festival, it may not be easy to by some hot lines of train, especially Beijing or Shanghai. Other places are fine.