From memory, there was a line at the start of TUC said somthing like.
"Sub-space shockwave orignated at ...." Subspace is TFL. Might be contrived somewhat unbelivable. But at least they tried to address why a ship light years away would feel it.
It was cheap and unrealistic, regardless of it being a "subspace wave" supposedly travelling at multilight speeds...
What really gets me though is this idea that Praxis is a Moon of Kronos... Let's see, we are given the impression that the Excelsior is cruising Through the Kronos system? This based upon Praxis orbiting Kronos and Kronos is the Homeworld of the Klingons? For this to hold water, the Excelsior would have to be Deep within the Klingon Empire at its heart... At least the novelization says that Praxis is orbiting some other planet or star and doesn't emphasize Kronos... But you can ask any fan today, and indeed read any novel like that "Shadows" one from the other year, and you'll be told that Praxis was orbiting Kronos...
I remember some years ago getting into a pissing contest over this online... Fans were telling me "Why Can't Kronos be on the remote Edge of Klingon space bordering the UFP!" and they were comparing it to known borders on Earth, for Gene's sake!