Is this accepted norm universally that a senior surgeon accepts the hernia surgery case and done clandestinely by his interns. Lie given to patient.?

No lies. Surgical training is accomplished mostly by trainees gradually performing more and more of an operation under the direct supervision of the attending surgeon. In the us, make no mistake that the surgeon is primarily responsible for every aspect of your operation, and takes that responsibility very seriously. While there are exceptions to every rule, you are getting who they say you're getting.
Can't answer. I am not implying that this is a clandestine process. Rather, the senior surgeon is present an directs every part of the case, that is, he/she ensures that your operation was done exactly as he/she would have done it.
Academic training. It is accepted. It is team building and foundation of surgical training. Younger surgeons are involved in every detail of your case and are often a big advantage. However, it is understandable to be surprised, especially if discussion about how this training occurs was minimized. Many patients ask, "are you the surgeon"? That is cue to talk about the team and how it works to benefit patient.
Training. Surgeons need training and if surgery is done under close supervision it will ensure good outcome, but participation of interns should be disclosed.