[4] From 1978 to 1982, he was the director and principal of UST Angelicum College in Quezon City and became its academic consultant from 1994 to 2002.

In the Dominican Province of the Philippines, he was appointed the socius or assistant to the prior provincial from 1977 to 1980.

[5] At the university, he was elected as dean of the Faculty of Philosophy from 1994 to 1996 and 2008 to 2012, and became the vice rector for religious affairs in 2010.

[5] In December 2021, Pope Francis conferred Castillo the Pro Ecclesia et Pontifice for his exemplary service and contribution to the Church.

[4] Some published articles in Philippiniana Sacra, the official publication of UST Ecclesiastical Faculties.