SITF confirms that this plant is Bulbophyllum aeolium (Feb 2023); POWO lists two forms for B. aeolium: subsp. aeolium (syn. B. sociale  and B. uniflorum) and subsp. padasense; this is the multiflowered B. aeolium subsp. aeolium (syn. sociale); correct based on characteristics in the description in Comber's "Orchids of Sumatra" of having a short column with short, rounded stelids; supporting photos may be found in the OW and several other on-line sources.