TCE captures only legal goods, so it can't show illegal goods, either in Trade Overview nor in Trade Advisor. It would be a bad advise from TCE to trade illegal goods.
EliteOCR or EDMC also didn't capture those goods, so they have to be added manually. Therefore I suggest to use the note section for illegal goods.
That is new to me, that these salvage goods could be traded (bought and sold), but perhaps you can make a screenshot, if you discover it again, so I add them to the database as default.
Nevertheless, you can add these goods as trade wares to TCE, if you like, but adding a good, that can't be bought but sold nor getting data about it, beside you having the good into your cargo, didn't make much sense for me.
Maybe I'm not being specific enough,
I'm not talking about special salvage goods but about regularly listed good that are legal in most stations but illegal in some, like
Combat Stabilizers, Personal Weapons, Battle Weapons, Narcotics, Tobacco, Slaves, Imperial Slaves ....
When you look at a station there is a list of Prohibited/illegal goods for that station.
I do not know if EDMC captures that list along with the market data and the rest, but if it does then that list could be used in TCE
to warn us that legal good in the station we are at are considered illegal in the station we currently have selected as our destination, so that we do not bring them there "by mistake".
Or that if we do, we are fully aware of the possible consequences.