We propagate salak by sucker division. In my experience simply separating them off and planting yields a poor result. We go to some trouble. We prepare a pot, about 1 gallon with some potting soil and make a cut on one side of the pot so that it can fit around the sucker and we tie a string around the pot so it stays in place. The potting soil needs to stay damp. We take a pruning saw and carefully make a cut about half way through the connection between the sucker and mother plant. after a month or so we make another cut about half way through the remaining connection. Wait another month and remove the sucker, transfer to a larger pot, and let it establish in the new pot, producing a new leaf or two that harden off. That should work pretty well.
Peter