The Chinese University of Hong Kong (CUHK) is a public research university in Shatin, Hong Kong formally established in 1963 by a charter granted by the Legislative Council of Hong Kong. It is the territory's second oldest university and was founded as a federation of three existing colleges – Chung Chi College, New Asia College and United College – the oldest of which was founded in 1949.
Chung Chi College, New Asia College and United College no longer exist at the present time.
The context says that the three colleges, Chung Chi College, New Asia College and United College, combined to form the Chinese University of Hong Kong . So it is correct to say that the colleges no longer exist the at the present time. The system may not understand that combining colleges mean they no longer exist independently