I forgot that zero fret, about the nut filings lool comment.
Anyways how I see it and as you said too, a heavily compensated saddle/bridge thing. Made for Aquila nylguts perhaps. And for other strings, better not so much?
My Kala concert I restrung it with Aquila strings too, because it was bought from "brick and mortar store". No compensation and I think it also works because sopranos need that and larger scale instruments, especially tenors not so.
Kala works fine without because it has a really low action. Good intonation without any saddle compensation. Something like 2.2 mm at 12th fret, but can't be sure. Anyways it is almost too low and I notice some buzz when finger playing hard, for strumming it is ok and a light to play in all my 12 keys chord progression practices.
About Flight TUS-50, it has a an action of maybe 2.75 mm at 12th, perhaps that is why also heavily compensated. Almost non existent relief when pressing 1st fret and 12th fret and in between space. It is so straight. Maybe a lower action would not need such a saddle compensation, or work with other kind of strings?
If you kept it and tried fluorocarbon strings, let us know?
Anyways this is so cheap ukulele and works just fine with the strings it came with. Though that resonance of A is so loud I am worried sometimes about damaging my hearing. It is so overpowering. Not with strumming, but with playing melodies with my thumb. Darn resonance