422 error occurs when the same task is running at the same time. For example, you start translating all products into French, and then you translate a single product into the same language.
LangShop blocks these manipulations to avoid server load and pops up the corresponding banner error. To avoid such cases, please wait for one task to complete and then start a new one.
Another reason the 422 error may occur is when you try to launch a new translation task, and it is on pause. To check tasks' status, you can go to LangShop Settings > Tasks.
Get to know the app better, learn more about Tasks.