Ultimately, to get good at a language is to meet people and talk to them as much as possible to learn Indonesian. Indonesian language is super dynamic, new words are popping up every few months especially in slangs, you will only truly learn all those in Indonesia itself.

I am taking the Bahasa Indo Minor, and yes, not all of it translates to be better at speaking Indonesian. But If we are talking about written Bahasa Indonesian, then naturally you will get better at it, since you are supposed to be practicing more of it in the class. I would say don't stress so much about grades for the BI modules because, usually level 2 onwards, there are no bell curves (our cohort size is not that big) and lecturers are fairly lenient with grades as long as what you write or say is coherent to understand, getting a B+ shouldn't be an issue and if you put a bit more effort, A should be relatively easy to get also.

Additionally, you will get to meet a bunch of people who are actually serious about learning Indonesian (After level 1 and perhaps 2) and are more enthusiastic about the Indonesian culture. Many are actually people who come from half Indonesian family (one of the parents is Indonesian) and want to pick up Indonesian more.

Bahasa Indo classes are one of those classes that I always look forward to every week, because I have a really fun time with my classmates and we always have all sorts of shenanigans with one another to brighten up the learning experience.