I don't have any experience with this plant, but it looks like the book says that Piper sarmentosum is the Latin name for komplou? If yes, you might find the Wikipedia page for Piper sarmentosum to be helpful: https://en.wikipedia.org/wiki/Piper_sarmentosum
Unfortunately it doesn't mention the name "komplou," but it does provide the names used in some of the countries near Cambodia as well as the name "wild betel." Some of the regional names seem to be phonetically close to "komplou" (e.g., cha phlu in Thai and japloo in Khmer). There's also a photo! It doesn't describe the flavor of the leaves, but if you decide the Wikipedia plant matches your book's plant, you might have luck finding info on other websites under those alternative names. Good hunting!