There is no state or national government oversight of home staging accreditations, designations or certifications. The certifications are given by the staging training providers, not an objective 3rd party. There are many professional home stagers without "accreditation" who do an excellent job. There are many professional home stagers who are accredited by their staging training provider. Look for the home stager with the most real world experience, with lots of home staging jobs under their belt. They should also carry home staging business insurance (liability) and all their employees should be covered by a workers comp insurance policy by law in CA.
I'm including a link below to an article about how to choose the best home stager.