An Equipment creature that loses its reconfigure ability cannot be attached to a creature by any effect.

A planeswalker with Tamiyo's Compleation attached to it may still be attacked and it will continue to lose loyalty counters if damage is dealt to it.

An attached Equipment with reconfigure that loses its reconfigure ability doesn't become a creature again until it becomes unattached, and it won't become unattached until the triggered ability of Tamiyo's Compleation resolves. If that ability is countered, the Equipment will stay attached to the equipped creature.