It is certainly possible that the Talmud knew a now-lost apocryphal book of Balaam. But the normal sense of the phrase "the portion of Balaam" (וּפָרָשַׁת בִּלְעָם) in b. Bava Batra 14b would be that it was a section in the Torah of Moses (as the English translation over-translates). Still, the "notebook of Balaam" (פנקסיה דבלעם) in b. Sanhedrin 106 in could conceivably be an apocryphal work.
That said, it is wildly unlikely that the sages of the Talmud knew the Deir 'Alla Balaam inscription. We know it only from a wall inscription in Jordan, written in an obscure Northwest Semitic dialect, and dating to a thousand years and more before their time.
For many PaleoJudaica posts on ancient lost books, start here and follow the links. For posts on lost books mentioned in the Hebrew Bible, see here and links, especially here and here. I published an article on the latter topic. The reference is here.
For posts on the Balaam inscription from Tel Deir 'Alla (Deir Alla), see here and links.
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