According to https://www.sttmedia.com/characterfrequency-indonesian the most common letters are ANEITK. Most typists these days have to think about how much they use English vs their native script. My take on locale variants is to add and tweak as little as possible to keep the efficiency of Colemak for English, while allowing a good experience of typing the other language(s).

Unless your left pinky is particularly weak, I'd try keeping the A in place for now. NEIT are in good positions in Colemak, so the only remaining question is K. This letter has an unnaturally good position in the QWERTY layout for typing in English†, so of course it's put away a bit in Colemak. On the other hand, unless you're using a matrix-type keyboard I don't find the new K position hard at all! Try it out a bit. To avoid same-finger bigrams like NK/KN, I recommend typing N with the middle finger in those situations. Similarly, if you need to type KE/EK a lot, use the ring finger for E for those bigrams. This takes a little training to get used to, but it's a lot more comfy.

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†:  (due to the layout's history of being partly alphabetic on the home row which shows in the sequence D_FGH_JKL)