Nice keris, bad rust
You should clean it the first time you have the chance. The blade's shape (dhapur) certainly not the ordinary one. The two deep fullers are intended to raise the middle part of the blade, so it resembles the body and tail of the naga snake. It is not the sogokan. Althought it is belongs to bugis family, I believe the blade was made in java , but not quite certain before handle it by myself
The Bugis peoples are well known as the good sailormen and merchants. They had travel throughout the archipelago for a long time, so it was very common for them to brought fine goods from other areas.
One more thing, I believe the blade is finely laminated. You may see the layers of iron under magnifier AFTER you clean it. So, just clean it Mykeris, certainly after you get the permission