Chief Medical Officer (CMO) is the title used for the senior government official designated head of medical services.
It was established during Queen Victoria's Rule in the 1800's, and it is used today within England's, Scotland's, Wales', and Ireland's governments to denote the single highest ranking civilian physician within those nations, on par with the military's Surgeon General. The very nature of the position is that there is only one within an entire government.
This would obviously contradict the established canon that NanoTransen hires multiple CMOs to work different shifts aboard the station.
Also, if the head of the medical department on the NSS Aurora is indeed THE Chief Medical Officer, that would mean that they were the highest ranking civilian physician in all of Biesel!
With all due respect towards Aurora Station, doesn't it stand to reason that working aboard a research vessel operating in the borderland territory of Tau Ceti is below the pay grade of Biesel's leading medical professional?
Surely, someone of such significant standing within the Republic of Biesel would be stationed within the capital city of Mendell, yes?
Now, within Wikipedia, you'll find a passage explaining how a CMO, by extension, is "the physician who is the professional lead of all physicians at a hospital," and so you might argue that, that is the case here, but consider that although a Colonel may be in charge of a military outpost, if the Field Marshal of the army is actively functioning within the company's operations, they would, by extension, become the professional lead of all soldiers at the base, you see?
We could assume that the occupational title of Chief Medical Officer within Aurora Station's universe is not equivalent to the corresponding position within our own, and that would be safe to assume seeing as how the term is most likely based on Star Trek's interpretation of the role, but then it comes down to whether or not the role play aboard the Aurora is based on someone else's fictitious canon, or rooted in established reality, and grown from our own design.
It should also be noted that Star Trek conducts military operations, whereas the NSS Aurora is primarily a research vessel, with supplementary mining operations. Seeing as how the two (presumably) exist in completely separate realities, this previous point is relatively moot, of course. I just wanted to touch down on the fact that between naval vessels, and civilian ones, the denominations differ greatly, i.e., Commander vs First Mate, and so on.
A Chief Physician, also called a Head Physician, Physician in Chief, Senior Consultant, or Chief of Medicine, is a physician in a senior management position at a hospital or other institution.
For the sake of establishing our own unique lore founded in reality, and not basing it off of the fabricated mythos of another's work, it is my impression that it would be more appropriate, and more immersive, to have NanoTransen hire various acting Chief Physicians to head the medical unit aboard the NSS Aurora Station.
If the role designation is to remain the same, then some things to consider would be,
(1) what is the title of the occupation that is the executive civil authority on medical services and public health within the Republic of Biesel, and
(2) what is the vindicating explanation that excuses the way in which the term Chief Medical Officer has come to designate a position that differs from what was previous established over the course of 200 years of human history.