Wow. This is really the lotto-players civ. You need islands, you need rivers, you need iron, and then you need to roll good abilities.
Candi does not need a river, it is an incredible UB. It can be built in ANY city, river or not, and it gives bonuses to you if you DON'T found a religion.
Indonesia is an awesome civ if you play it right.
I agree the Kris swordsman is sort of meh, but it just doesn't matter. The UB and UA work so well in combination that Indonesia is just an awesome civ to play.
In all my games, Indonesia is a wonder spamming war monger. Yeah. A wonder spamming war monger, thanks to that Candi and the UA.
Here is the Indonesia game plan I usually follow:
1. Treat Indonesia as a "one city challenge" for the first half of the game.
2. Initial build: scout, scout, granary, library, buy a shrine as soon as 250 gold, and steal a worker
3. Go tradition, beeline to the extra food in capital, then get aristocracy
4. Beeline henge, oracle, and then national college then build the candi and the national epic
5. Found a religion but DO NOT SPREAD IT. Get feed the world and then defender of the faith. For a pantheon pick what suits the capital prioritizing food/growth/faith
6. Try for one of the religious wonder like hagia sophia or borobudur then build all the other national wonders especially the grand temple (yes grand temple) and heroic epic, also ironworks, circus maximus is great, east india company if you are getting trade routes, etc, as well as the guilds
7. Beeline education and get universities up and prioritize oxford
So what's going to happen here? Jakarta is going to become a truly massive city full of a zillion specialists. You are going to spam great people, and settle them. You are going to have a religion and you are going to be pumping out a decent amount of faith. But you are NOT going to be spreading that religion -- you are HOPING that other civs will spread as many religions as possible to Jakarta, to get even bigger bonuses out of that Candi. You are going to be the happiest civ on the planet and you are going to go through golden age after golden age. You're going to have lots of cash for buying buildings, and if necessary an even bigger army, as well as eventually settlers, and then obviously later in the game bribing CS.
So what are you doing with all that faith? Spewing out military units with Defender of the Faith until industiralization, and then buying even more great engineers and great scientists. Meanwhile the capital is constantly working on buildings, wonders where you can get them, otherwise just upgrading and upgrading and upgrading into a massive powerhouse.
Buy some settlers after astronomy and settle advantageous spice islands, you won't suffer ANY happiness penalties while you expand out, because you get free happy resources every time you settle a city, which is AWESOME. These cities will start with a lot of free buildings thanks to your advanced culture and you will have tons of cash to upgrade them rapidly.
I love playing Indonesia and I think it is massively underrated.