How can I be sure? Simply by citing the Talmudic verse itself; It’s self explanatory:
If you seek the origin of the word 'syrup' in Gentile sources, such at Merriam-Webster or Online Etymology Dictionary, you’ll be led astray to many other languages, but never to Hebrew that outdates them all.
There are two further related indicators:
1) The source is a product that oozes from a tree.
2) The word שרף also comprises the verb to burn. Again, and quite obviously, it’s made to burn for it comes from a tree, as logs are the quintessential form of fuel. In fact, these resins were created as flammable to yield a wonderful aroma - thus the source of incense.
(As for the same word “שרף” that also defines some rank or type of angel, this too has to do with “burning”, perhaps in appearance or in metaphor, but of this I know too little to comment.
This word may also relate to "serpent" - whose bite delivers a burning sensation, unlike the scorpion's that is cold.