This post follows on the previous post here, as well as other posts such as here.
The one-way speed of light is a convention (see John A. Winnie, Philosophy of Science, v. 37, 1970). The two-way (round-trip) speed of light is known to be c, but the one-way speed may vary between c/2 and infinity, as long as the two-way speed equals c. This means that those who say the light from a star took X light-years to reach the Earth are speaking of a convention rather than an actual duration.
A convention cannot be “cashed in” to become reality. For example, one cannot adopt a convention that some pebble is worth a million dollars, and take it to the bank and expect them to exchange it for a million dollars. According to their convention, it is worthless. If both follow the same convention, they can make the exchange, but even then it is based on a convention, not on an intrinsic reality.
Similarly, the time for starlight to reach the Earth cannot be cashed in for time on Earth. If the one-way speed of light equals c, then some galaxies appear to be billions of light-years away. But this time is the result of a convention, not an actual duration. This time cannot be cashed in to be an actual duration on Earth. Conventional years are not actual years.
It’s well-known that all motion is relative. That means what bodies are in motion are relative to a frame of reference, and there is no preferred frame of reference. Ironically, Galileo Galilei, who is credited with discovering the relativity of motion, is also known for claiming that the Earth moves around an immovable Sun rather than the converse. Whether the Earth or the Sun moves is a convention relative to a frame of reference, not a reality that all should recognize. Whichever convention is adopted cannot be cashed in for a state of rest or motion.
Conventional science is science with standard conventions. Unconventional science is science with non-standard conventions. Both are legitimate forms of science. Their conclusions should be the same, even though their conventions are different.