What is the Correct Sense of 隔空喊话 in English?
According to the examples you provided:


Two parties seem to respond and talk to each other but actually not. They say something one after another which looks as if it's on topic, but in fact the things are attached to the same topic literally.
Express some opinion that can lead the consensus, or just talk to the public related to one party itself, without condisering the other and the two-party conversation.
Pretend to express something but actually not have that in mind, not sincere. Or 说空话.


I think it's not easy to find an accurate English counterpart. It's something like only seemingly talk to the other party but with some purpose (involved in other topics, or even be malicious) in mind.