Fast forward a couple hundred years to1923. Edwin Hubble measured the distance to the Milky Way’s closest neighbor, the Andromeda galaxy. His measurements reveal that Andromeda is not a collection of gas and stars within our own galaxy, but an entirely separate galaxy. The universe is suddenly vastly bigger than we once thought. This lead to the belief that there were thousands of other galaxies. Six years later he demonstrates that the universe is expanding in 1929.
If earth was 50% larger in diameter gravity would be so high that chemical rockets would'nt be able to break the earths pull and our intire space adventure vould be nothing but a Jules Verne story.
So if the folks at Kepler 425b are like us we're just a story and a dream for them, nothing they can come and see.
My point is, it's too far way for any of our instruments to measure the 'actual' habitable zone of that system. Too much guesswork going on.