KDean11 Thread moved to Tech Support.
I tested this, and observed the same thing as you.
Nauzicaa Brigade was able to kill Jade Figurines produced in two ways:
1. Artefact Compression on an Emissary (spy by default) and
2. Artefact Compression on a Wyvern that I'd used Infiltrator on (loyal card turned into a spy).
(Using Artefact Compression on an Assassin whose Spy token I'd removed with Infiltrator
did not allow Nauzicaa Brigade to kill the Jade Figurine.)
So, cards with Spy tokens that are turned into Jade Figurines can be killed by Nauzicaa Brigade, regardless of whether they have the token by default.
Definitely seems like a bug.
Edit: Tested further in friend matches, so that the Artefact Compression was played by my opponent. I wanted to eliminate the possibility of
my using AC enabling NB to kill the JFs.
Results were the same: Nauzicaa Brigade killed the Jade Figurines produced from a spying Emissary and an Infiltratored Hawker Smuggler, but not the one produced from an Infiltratored Assassin.