Barack Obama is reported to speak Indonesian as result of the four years, from age six to age ten, that he spent in Indonesia. From what I know of his life since, he has not had much opportunity to improve or even keep up his Indonesian. He doesn't seem to have returned to Indonesia for any significant amount of time or to have had other Indonesian speakers in his life. I would therefore expect him not only to be quite rusty but never to have attained full adult competence. He would not be likely to have the vocabulary expected of an adult, and he might not have acquired some of the syntactic structures. He would also not control some socio-pragmatic aspects of the language, such as the more formal stylistic registers and when to use them. This isn't to dispute his claim to speak Indonesian, but to point out that unless there are factors unknown to me, he may well be able to carry on simple conversation in Indonesian, but he is probably not able to carry out political negotiations with Indonesian leaders in Indonesian, or even to understand discussions of topics like politics and technology in an Indonesian newspaper, for which he likely lacks the necessary vocabulary.
Does anyone know of evidence as to the level of his ability in Indonesian, and if it is higher than I suggest, how he acquired it?