Isn't engineered fill just any fill that is to be placed for an engineering purpose, ie. building pad, road bed, dam, ect? Not that I'm proud of it, but I've had engineers from my company approve just basic silt for a regrade, I believe it was for a set of apartment buildings. I didn't do any of the testing, so I'm not sure how that came out; hopefully it wasn't wintertime. I think trench backfill wouldn't necessarily be engineered, being that is just somewhere to put the dirt back after you've dug a hole, not that it shouldn't be compacted. In my experience, engineered fill is fill to be used for an engineering purpose, all properties aside.
