They mean that the FOV seen by the phone through an eyepiece is too small to run a successful plate solve.

The comment of the user says "the plate solve was precise enough that the object I wanted was centered (for the observer, not for the phone) when I used a 5mm eyepiece" (which is usually an high-power, meaning tiny-FOV eyepiece)

Most pointing methods aren't accurate enough to correctly center an object at high power and require you to use a lower power eyepiece, nudge the object a bit, then switch to high power. I understand how you read it as slop but the two sentences aren't contradictory, and the user comment hints to an useful pointing tool :)

Edit : bad tenses and grammar fixes

Thank you for the explanation!