Sounds like you saw the St Joe Switcher (J747 or J748 if I remember symbols correctly). Crew is based at Trautman yard, which is pretty well the EAST end of their customer responsibilities. (The tank car customers along the double track closer to Cincinnati, CGB at Riverside , and the Port of Cincinnati at CP Oklahoma are served by a yard job out of Queensgate). Just east of Trautman is a CGB grain facility (former Indiana Grain), then (going west) is CF Industries (fertilizer - tanks and covered hoppers) Kinder Morgan/River Transportation (Rail to River/River to Rail facility - all sorts of traffic), future Lone Star site, CGB Northbend (grain, fertilizer, coal, coke - covered and open top hoppers), CIND Interchange (all sorts of traffic), another fertilizer terminal who's name escapes me at Ft Miami (covered hoppers), DuPont at Ft Miami (tankers - sulfuric acid, etc), then CGB at Aurora (Coal, Coke, Pig Iron/HBI, grain - covered and open top hoppers, gondolas). Crew then runs around train at Aurora in what tracks remain out there and returns east. They work customers in both directions - for example, CGB Northbend plus inbounds to CIND are worked on way west, and cars from CIND are picked up on way east.
Coal cars you saw where likely either coal or coke off river loaded at one of the CGB docks.