Do you know for a fact there are any ePub format books published in Bahasa?
If you are connected to the iTunes store in Indonesia or Malaysia there may be some Bahasa iBooks in the store, but I don't know if any are even available.
If you look over a wider range of readers - i.e. not just iBooks but ebooks in general - then you'll find some. But the lack of books in Bahasa is simply a reflection of the lack of authors and/or publishers providing material. For sure, Apple have no policy here and I'm sure they'd welcome additional titles with open arms.
You need to contact publishers and ask them to do the translation for titles you are interested in. Apple is only a reseller. They will not be translating books to Basaha I'm afraid...