People from Indonesia, Thailand, Philipine or India found this tree very easy; most of them called it Jambu air (water apple), wax apple, java apple, chomphu (in Thailand) or bell fruit, makopa (Philipine).
Syzygium sp parts of Myrtaceae family. Enjoy the complete members here: A Monograph of the Genus Myrceugenia (Myrtaceae) (Flora Neotropica Monograph No. 29)
Interesting readings about Pontianak:
In Centraal Borneo: Reis van Pontianak naar Samarinda (Dutch Edition)