Calling the distinction you made artificial actually hinders your own statement:
1. You create the distinction to suppose Mihawk's title is fraudulent
2. The distinction actually shows the title is not fraudulent, when you consider the concept of trying to isolate a very small portion of the world (where celestials live and Imu resides) from the rest of the much larger world being artificial in and of itself.
3. The fact of the matter is Mihawk is currently the best, until he's defeated. Just because a demon god and his leeches that siphon his power (like shamrock or garling) choose not to interact with what they dub the "lower world" doesn't change the fact that within the 99.9% of the rest of the World Mihawk is the strongest swordsman.
4. The title itself is logically sound, and that 0.1% of the world is still free to contest it (but chooses to hide itself)
5. You can even Argue Imu's leeches are also weaker swordsman in general in terms of skill and haki utilisation in swordsmanship, but even if they could technically have more strength than Mihawk, it's not a result of their own strength anyway since they are leeches.
The God's knights essentially are and represent Imu, when you fight a gods knight you are fighting Imu because they are using Imu's power and Imu has full control over their bodies. They are essentially transparent in the world compared to everyone else, especially when it comes to powerscaling, they don't even have their own complete agency in-tact. That's what Imu's contract and dominion means.
So really Imu himself who chooses to be in the shadows is really the only person on the planet that could be considered outside the realm of Mihawk's title. (More on this in 6.1)
6. If you say that makes Mihawk's title fraudulent, you don't know what the word fraudulent means, because that involves acting with a plan to trick people.
So are you trying to say Mihawk is trying to trick people into thinking he's the strongest swordsman like Buggy is trying to trick people?
"Oh hey guys I'm stronger than the unknown entity that sits on the empty throne, that you don't know exists"
6.1 Not to mention the fact that Imu's true nature has been stated to be like that of a "God" and not a man in the first place, so why would he make Mihawk's "Strongest swordsman" Title false, if he is some type of demon like entity with a god like nature, and immortal instead of being a mortal man.
This is why Mihawk's title is still in-tact. You can actually argue both WB and MIhawk's titles are more in-tact than Kaido's vivre card statement. And that Kaido is actually the most fraudulent because he's called the "strongest creature" which Imu falls under regardless of his nature.
