Did you know there's an allowable amount of insect parts and rat feces that can be in your food without any particular labeling required?
There is no known process for removing bones from chicken that is perfect.
That said, something that is large enough to be described as a "long, thin bone" by a reasonable observer should NOT be allowed in something labeled "boneless", and the restaurant and any other entity involved in the deboning should have shared liability. If the process is accurate enough, the liability risk is low.
(or something like that)