Nope. That confuses me too though so I'm in the same boat as you.
I know it's not "Hacks" though.
"Hacks" requires the user to edit game files to their convenience. Although editing untradable tele's isn't possible from the users game files (I think, never cared to look into it cause I like to play all games legit, personally.).
Uhm, some tele's are tradable somehow but the starter one's you get on your character are NOT tradable. to prevent people for making new accounts constantly and characters just to trade tele's to theie main.
Of course, though there IS the making of multiple characters to put the tele's in the account stash then deleting them which is where the wonderful 7 day deletion period takes effect. Which is a good counter for people who would try doing that.
Not sure though like I said, I've seen some tele's for sale for a long time, etc that say untradable but they are being sold in catshops and stuff. Not sure if it's allowed or not. Any tele's I get from cash shop I use so never bothered trying to sell since idk if I can get in trouble for trying to 'merchant' tele's on the market. o_o