The name Balam invites comparison with Balaam, the seer of Numbers 22 to 24 who is hired by the king of Moab to curse Israel and blesses it instead, and whose donkey sees the angel he cannot.
The case is better than most of the derivation claims in this catalogue, for a reason that has nothing to do with philology. Balaam is not merely a figure with a similar name; he is the Hebrew Bible's archetype of the hired diviner, a professional practitioner of exactly the art the Goetia describes. Later tradition treats him harshly, the New Testament uses him as a byword for corrupt teaching, and rabbinic literature develops him into an outright villain, so a Balaam-derived demon of divination in a grimoire has a coherent history behind it.
The case is still not proof. Nothing in Weyer or the Lemegeton makes the connection. The Goetia's Balam has three heads, rides a bear with a goshawk on his fist and speaks hoarsely, and none of that comes from Numbers. Weyer gives the name as Balam and also as Balaam in some readings, which either strengthens the case or shows a copyist making the same association a modern reader makes.
That last possibility is the recurring difficulty with every derivation in this corpus. A name that half resembles a biblical figure is very likely to be assimilated to that figure by someone in the chain of transmission, at which point the resemblance becomes exact and the evidence becomes circular. Without a manuscript stemma showing when each form appears, the question cannot be closed, and it has not been.