[this is my country]

Irrelevant, since under both US and Indonesian law, he never lost his US citizenship.

It, certainly, is relevant if he is, presently, a dual citizen and did not reveal that fact when running for President.

[curiosity]

It, certainly, is relevant if he is, presently, a dual citizen and did not reveal that fact when running for President.

It's legally impossible for him to be an Indonesian citizen. US law did not allow minors to renounce their citizenship or lose it on account of the actions of their parents. Indonesia did not allow anyone to become an Indonesian citizen unless they renounced or lost their prior citizenship.