At the moment, the only time tickets are sent to the server is if you attempt to download something off the eShop. This isn't likely to change because Nintendo mostly has stopped caring about the 3DS, they had years to implement these kinds of checks and they never did. So you don't really have to worry about Nintendo seeing unsigned tickets on your system and banning you for it, as long as you don't try and use the eShop with them.
You can safely use the eShop, as long as it's to download stuff you legally obtained. Attempting to download/re-download something with an invalid ticket will fail, and since the ticket gets sent to Nintendo, they can easily log it, and possibly ban you later. So don't do that.