Sometimes the staff of those restaurants may not be proficient in English, thus resulting in errors in communication with foreign customers or make them miss the store's most popular dishes to customers.
Sometimes the restaurant staff, they may not be proficient in English, resulting in an error in communicating with foreign customers or causing them to miss the introduction of popular food to customers.
Sometimes those restaurant staff may not be good at English, so result in mistakes in communication with foreign customers, or they fail to introduce the popular food of the store to the customer.