Never
This is incorrect; in addition, what was LT's first appearance? The Beyonder's? TOAA's? That kills that argument, yes?
The original Beyonder was NEVER "God" or even "God level."
And you do know that there exists myriad other Beyonder-like beings in the universe The Beyonder inhabits, yes?
The Living Tribunal was powerless against an entity that Dr. Doom DEFEATED? LoL, okay let's say he was...where in comics is this said?
I'll try to clarify this. The Original Beyonder (before being reconned) was basically all powerful and not even the Living Tribunal was its equal.
This myriad of other Beyonder-like beings is after the Beyonder was RECONNED. Before this, Beyonder was the only one of his kind.
Doom used Galactus' power to battle the Beyonder and take his power. It wasn't just Doom himself who did it. And I'm aware that LT> Galactus; however, Spiderman also kicked the entire X-Men's ass during that series, somehthing he shouldn't have.
As for info about Beyonder greater than LT, I'll have to look it up again but Beyonder erased Death from existence and nobody was able to stop him, including LT.