Moths are extremely difficult, not to mention Sumatra have many endemic species.

In your specimens, the yellowish margin which is broad at the costa goes fairly broadly round the apex to the distal margin.


In both the Brunia species it narrows at the apex & goes narrowly round the distal margin.


B. antica Taiwan & Japan where B. sarawaca is absent.
http://twmoth.tesri.gov.tw/peo/MothI...7-20151127-016
https://www.google.com/imgres?imgurl...act=mrc&uact=8

B. sarawaca thi from BOLD is probably correct.
http://v3.boldsystems.org/index.php/...e?taxid=596084
http://v3.boldsystems.org/pics/LEFIJ...1522152732.jpg

You can also see both species in this article.
https://www.zobodat.at/pdf/ENT_0038_0141-0176.pdf

From this it should be Eilema ,E prabana is a good candidate.
http://www.jpmoth.org/~dmoth/Digital...%20prabana.htm

I have no idea of the other Eilema species you mentioned.

TL Seow: Cheers.