I have this thought that probably is dumb. But regarding the problem to measure the speed of light in one direction, we know the refractive index is $c/v$. Now, by measuring the refraction we can arrive at $c$. Also since this experiment is done in one direction, is this experiment not measuring the speed of light in one direction and arriving at $c$?
"by measuring the refraction we can arrive at c" - No, that's not true. We also need to know v i.e. the speed of light in the medium in order to determine c from n. If you want to determine the speed of light in one direction in the medium you then encounter the same problems as when you try doing this in the vacuum.
For more on the problem I recommended this interesting stack exchange entry:
(It is stylistically interesting that both you and the person who asked the previous question started with a version of "my question is probably dumb" , which you really do not have to do!)
Okay, that experiment is not actually measuring the speed of light in one direction as other have pointed that out. We can't get to v without actually measuring it in both the directions.
And, IF the speed of light is less or greater than c in the direction we are doing the experiment ( which is spooky to me), v will also adjust so that n is constant. That basically means we have no way of knowing if c is constant in all the directions.