Requesting Details on Index Cache autofill

[Marxon1134]

So I've noticed the ingenious new feature 1.6.5 is showing where its adding new items to the list when it sees it in the save file once.
I was wondering where its storing the data for these new solaris dlc items.
Example: While the xml files don't list it, "LightRifle_Burst_Lvl3" and "BM_Arena_ActiveProbe" show up in the drop down now because my save had them at one point.
Is the data for these newly added indices stored somewhere like in the unified data cache? (which I can't figure out how to read yet) or somewhere else?
Asking ahead of time in case modding efforts result in making a bad index identifier for a modded item and therefore having a need to edit or remove it.

[Marxon1134]

UPDATE
Theoretical issue is no longer theoretical.
Attempts to load a HGN-VEST mech into the cold storage results in HGN-733PP instead.