Is the collection certificate of Northwest Headquarters of Chinese Calligraphers Association authentic?

yes. According to the query of Douding.com, China Calligraphers Association is a subordinate unit of China Federation of Literary and Art Artists, China Federation of Literary and Art Circles is a subordinate unit of the State Propaganda Department, and China Calligraphers Association is a subordinate unit of China Oriental Painting and Calligraphy Group, which is a formal department and is true. The Chinese Calligraphers Association was established in 199 with the approval of relevant state departments, with the aim of promoting the art of calligraphy and painting in China.