Syncing doesnt work, dont get based on what you see on their site.
In short terms, just started my store and connected with CJ and sold my chosen product directly, they say that inventory sync automatically with your shopify store once you connect and i was checking that they had +10k pieces per each size and was pushing with ads, on first fulfillment i asked to do they open me a ticket saying product will get discontunied but we can ship this other product which is similar but it wasnt it had lots of different things which my customers will notice about