We found a peat swamp forest with a stream inside at Betong area in Sarawak which "felt" exactly like the one we found in Rompin filled with C. cordata. The stream had barclaya growing inside it and barclaya was a good friend of cryptocoryne in our opinion as they were frequently found together.
However, my friend "disturbed" some locals bathing in the stream when he ventured into the forest and we decided to proceed on to another area first. However, after driving for a while, we kept discussing that the forest definitely had cryptocorynes inside and giving it a miss would be a waste and thus we headed back.
We were right! After bashing deeper in, we found an entire carpet of emersed cryptocorynes covering the soft ground of the swamp forest. The shape of the leaves looked like that of C. longicauda and we soon managed to locate some unopened spathes to confirm their identification.