I have no idea what could have caused it. While one cursed wand effect turns the wand into a different item, additionalzaps caused by wondrous resin never do that.
The effect which let's you see all items on a floor after you step into a well of awareness (which was also granted by the talisman of foresight before it was reworked) isn't tied to a specific floor. As such, you can scry multiple floors if you manage to switch floors before the effect ends.
So I can no longer scry multiple floors at once? 😞
This exploit has existed since vanilla AFAIK (although it was rendered mostly useless by the talisman rework).
That's not a simple answer since damage reduction provided by stone depends on your evasion and enemy accuracy. However, at low arcana levels stone definitely beats viscosity since the boost goes into increasing the portion of damage deferred first before providing any actual damage reduction. At very high levels, though, viscosity wins since stone is hard capped at 75%.
In your case specifically, damage would be reduced by ~80%, definitely outperforming stone.
Is it an old save file? This could have happened as artifact generation code changed between versions.