What happens if nether ore (palladium) has negative values for X and Y in the config?

Thank you for the informative answer. Looking forward to that feature, in the mean time though I will go ahead and fix that spawn range. Thanks again

Considering it spawns exclusively in the nether, this would likely just break the ore spawning since spawning it out of world isn't possible. The only time you can have a height range outside the world is with the trapezoid height range (where the ores spawn more often in the middle of the range).

Manually selecting trapezoid ores will be configurable once the next update rolls out. For now I recommend avoiding setting your ranges outside the dimensions heights.
For Overworld this range is from -64 to 320, and for the Nether it is from 0 to 128. I am unsure what exactly it is for The End.