I only remember international media in late 90's and early 2000's talk about British protesting on Hawk being used in Aceh against rebel insurgence.
I believe Hawk's is being used..since the only fighter squadron that located in Sumatra at time, is Hawk 209/109 sq in Pekanbaru.
Besides, it's period where after East Timor fiasco, Indonesia still facing Western embargo..and also the economy still highly affected by Asian Economy crisis 98. Thus Hawk with relatively new airframe plus more economics to maintain, is also one of the most operational readiness.
However most Air Cover in Aceh operation done by OV-10. Afterall as COIN aircraft, it's most suitable to handle rebel insurgencies.
Officially East Timor, Aceh, Papua insurgencies being handle by OV-10. However there are some media report International and Local that witnessed Hawk operation. That's where the British protest coming from.
This is the sample on official position:
Indonesia uses UK Hawks in Aceh offensive
Officially, the Indonesian Military will not confirm or denied usage of Hawk in insurgence operation. However considering Hawk sq is located in Sumatra, and limited number of OV-10 available (there are already some attrition from previous operation in East Timor). In my opinion it's inevitable some flight of Hawk being done in Aceh.
Still based on publications on those insurgencies operations..The work Horse is OV-10. This is the plane that as soon as came from US, already put in operation tempo in East Timor replacing P-51 and B-25/26.
OV-10 is the most popular fighter for Indonesian Troops in the ground. They see it just like GI's see A-10 in Gulf..a life safer..