[ngoma]

This is an expected idiosyncrasy of refitting the IP top cover.

The fuel limiter screw (sometimes called "smoke screw" or "fuel screw") screws into the top cover and acts on a lever going deep into the main IP body.

The top cover screw holes are larger than the attaching screws, so there is some slop on the top cover final positioning on the main IP body. Side to side, front to back, twisted either way, the top cover can easily be reattached in a new position different than it was before it was disassembled.

The natural result is that the fuel limiter screw may need to be re-tuned after refitting the top cover.

Your question "can any adjustment in this area make fuel consumption worse," well yes, the fuel limiter screw has a direct impact on fuel consumption. If it is screwed in too far will cause overfueling, feeding more fuel than the engine can efficiently burn. The visual clue here is excessive soot out the tailpipe.

Some cut the anti-tamper collar off, to make adjustments easier.

As far as increased fuel consumption, would need to see the numbers, compared to similar weather conditions (colder wintertime temps always increase fuel consumption for me ~15%) and usage conditions (a long trip-- more constant speed highway conditions usually consume less fuel than in-city stop-and-go driving).