Isn't Teleport an Effect that bypasses walls and objects?
It bypasses walls and objects in between zones A and B, but not those inside of zones A and B. If you enter or leave a zone, even via teleport, you still cause all enter zone triggers and leave zone effects.
Perhaps we can clarify that teleport also cancels a previous attack trigger. That would support Shadow's description and provide more clarity around the concept of a 'trigger'.
That is true, but it has to be kept in mind what the ramifications of that would be. It would completely fly in the face of the rules on Damage Barriers currently. Sure, we could write out an exception to Damage Barriers, but I really don't like that nor see the necessity. It would just make the rules more clunky and convoluted. If people want the attack from Mangler Caltrops to be negated, then the easiest errata I think would be to turn them into a Melee Attack. I'm not sure why people have a problem with them still getting their attack though.
You did enter the zone. You had to set foot there in order to trigger these cards, thus you must have stepped on a Caltrop. You might have instantly been teleported when you set your foot down, but you were still injured.