I don't think I'd assume that feeding issues would be probable.
After all, length to diameter the 9x19 isn't much different of a ratio than .45 LC and .44 S&W Special, both of which have been successful in that platform.
Plus, the tapered case would feed better than the straight-walled revolver rounds, and the .45 LC barely has a rim, so being rimless I don't see the 9x19 as disadvantaged.
I see a couple reasons why a lever 9x19 would be nice; as a companion to a sidearm in the same caliber, longer sight radius and a capacity (in rifle length of 12-14 rounds), and as a levergun they are every bit as effective/lethal as EBR's but don't look like it, so they're unlikely to draw legislative scorn anytime soon.
If long-barreled 9's had no place we wouldn't have semiauto carbines; ANY caliber can usually be improved with handloading, and pistol calibers used in longer barrels often utilize slower powders than their factory loads.
I probably should have started this thread in the levergun rifle area rather than general, but I didn't notice that option at the time.
The original question still stands: has anybody produced a 9x19 levergun?
To ban guns, you must first ban knowledge of guns.
To ban knowledge of guns,
you must first ban knowledge itself."
- L. Neil Smith