Horizon, Bright moon, Sabre (first published 1974-5) is definitely still under copyright protection. I believe the copyright laws in British Hong Kong (The Copyright (Hong Kong) Order 1972) at the time is 50 years and definitely cover translations as derivative works. The situation in ROC is murkier as it wasn't a signatory of WIPO Paris 1971 and only adopted life+50 years in 1992 (previously life+30y), but as this extension came within the protection period it should be assumed that it is life+50y. I couldn't find English translation of the original text of the Copyright Act but a chinese version of each iteration of the Act is here. Anyway, the upshot is that WIPO copyright protection is in place until 21 September 2035.