You can check the order priorities only for own orders by using the Order Book Detailed Information Request/Response Message from Virtual Servers (Query).
Please refer to "System Interface Specifications for arrowhead - Operation (Query) " for Order Book Detailed Information Request from Virtual Servers (Query) and the following FAQ.
URL:
https://faqsd.jpx.co.jp/faq/show/3985?site_domain=en_application