If applying for CSA, and you get invited to the assessment day, make sure that CSA is your choice of employer. Once you sit your sim check and medical assessment, these form your actual CAAS licence application. They are held by the airline, and will not be released to another employer. They can be done once only.
Therefore if you prefer to look at other airlines options, after completing a so called interview sim check and medical, I understand you cannot.
This is China.