pEmitter's a little different than most tools because it has separate controls for X,Y, and Z rather than a Center control, even when the particle system is in 2d mode.
In the pEmitter's Region tab, right-click X Offset and choose Connect To > Tracker1 > Tracker 1: Offset X Position (3D Space)
Do the same for Y Offset. The pEmitter will not immediately update, but if you step forward or backward one frame, it will snap to the right place. It will also appear to have the wrong numbers—that's because it's projecting screen space into 3d world space, but as you can see from this screenshot, the pEmitter's circular region is in the right spot according to the Tracker's Center.
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