Speaking about tag-questions. I've come across such a dilema. Let's take two sentences "He has not been studying" and "She has never called him back" and make tag-questions. We will get "He has not been studying, has he?" and "She has never called him back, has she?". So for both sentences, one of which is in the Present Perfect Continuous Tense and another one is in the Present Perfect Tense, tags will be the same? Am I right?
Yes. It's only the first auxiliary verb that is used in the question tag,