When changing items that were most recently added to the default item list then name changes back to default next time you load Z-Quest. It seems only to effect then name and not the item data.
Example I changed the wealth medals into Triforce pieces. Save the quest and close Z-Quest. The next day, I load up my quest and discover that my custom Triforce pieces are now called "Weath Medals" again.
I can confirm that this happens with all three wealth medals, and the Peril Ring. I can also confirm that this does NOT happen with the Blue Candle, as well as several other more traditional items.
I suspect that its the new batch of scripted items that were added not too long ago.