What happens when something is put on the scale while it's sampling? Does the curve depend on properties of the scale, or just properties of the object and the manner in which it was put on the scale?

It's the latter. The scale is meant for real-time monitoring of rapidly varying force (the primary application is about monitoring the force derivative and repeatable max force logging). It uses an aluminum load cell if you're familiar with those, there's a tad of a multi-kHz resonance that is typically overshadowed by the object properties.