I'm in the process of writing my own silly list which is kind of related to this. So the wiki article was useful to me. There are some things I don't agree with though.
Possession is listed under "when you trash a card" ("The card is set aside and returned to the discard pile at end of turn"). Here it's from the perspective of the player being Possessed. But under "when another player would gain a card", "at the end of the turn", and "after this turn" it's from the perspective of the Possessor. Not sure how to fix it, but it should be made clearer.
In games using this, when you buy a card
Embargo, Hovel: Why "in games using this"? Hovel can only be trashed from your hand if it's in your hand, and Embargo's Curse gaining happens from the tokens, not Embargo itself being in the game.
State timers
I don't find it useful to view "while this is in play" as a trigger. I suppose it could be shorthand for a "when this enters play" trigger pluss a "when this leaves play" trigger (with the first event describing the change and the second describing the reversal). But I think it's better to think of it as describing a state. I call it a state timer. The same goes for "during your buy phase" and "in games using this".
Goons has the state timer "while this is in play". The state is that the trigger "when you buy a card" is in effect, which it isn't at other times. Highway has the same state timer, but the state is just cost reduction. Bridge has the state timer "for the rest of your turn", and the state is cost reduction too. The state timer itself is in effect when Bridge is played.
Most states are that some event trigger is in effect, but some don't have anything to do with event triggers: Peddler, Highway, Princess, Quarry, Band of Misfits (under the "while this is in play" heading).
I'd also argue that Lighthouse doesn't have the "when another player plays an Attack card" trigger, in spite of the wording. No event actually triggers when another player plays an Attack. Instead it just has the "while this is in play" state that Attacks don't affect you. Moat also has that state, lasting for the rest of the particular Attack, but only coming into effect when you reveal Moat as part of the event triggered by the "when another player plays an Attack card" trigger.
Watchtower: The "if this is in your hand" header seems pointless for Watchtower. It's simply "when you gain a card", just like Royal Seal, although Royal Seal also has the "while this is in play" requirement.
Grand Market: You don't need both the "when you would buy a card" and "while Copper is in play" things. They say the same thing. I would keep "while Copper is in play", which is actually a state timer.
Contraband: I guess a when-would-buy trigger works, but I would make it a state timer instead, like for Grand Market (both being "you can't buy..." states). So "during your buy phase", just like for Peddler.