It’s probably millions, not trillions. But you’re right, it’s so far that the difference doesn’t matter anyway. If it was 50 light years and they were going to crash together in the next 5 minutes, we’d never feel any effects. Probably bad for grandkids in their later life, though.
Well.... When it comes to interstellar "events", it's the stuff that's already happened, but is some distance away, that can get us. For example, if an exceptionally massive star 5,000 light years away, collapsed, sending out a gamma ray burst, 5,0000 years, +8 hours ago (this stuff DOES happen, though rarely in our neighborhood - I think the figure I read was every 5 million years or so in our galaxy), and it happened to be aimed at us, the astronauts on the ISS better get to their radiation shelter, fast. Earth's atmosphere would probably shield most life on Earth, so, contrary to hyperbolic vids on You Tube, etc., we probably WON"T get fried for breakfast tomorrow, but, Earth's atmosphere itself may be damaged -- likely not enough to cause an extinction level event, but UV light getting through from our own Sun may increase significantly for some years afterward.
Now, what might happen and how far the effects might reach from a collision of 3 incredibly massive* black holes that occurred 300 million years ago, from a location 300 million light years away - honestly, we really DON'T know... yet...
*It's almost as hard to get my head to "wrap around" that much mass, as that much distance. :-)