He has 17 TDs and 2 INTs in his last 7 games. I'm not sure what else can be expected of him. He's missed some throws but who doesn't? I say this as somebody who was not a Goff fan at all at the time of trade but he's been good pretty much since Lynn was let go and they let him throw beyond 3 yards.
If an upgrade is available (Lamar for instance) then it should be explored but I actually think this offense suits Goff very well with the elite offensive line, good running game and guys like Swift and Amon Ra who live in the intermediate and closer range are benefitting greatly from an accurate QB like Goff. I see your concerns with Jamo's potential not being maximized because Goff isn't great on the long range throw but Jamo is much more than just a run deep and catch guy so he'll be fine.
Minnesota will be a good test. Lions QBs typcially get eaten alive in Minnesota for as long as I can remember so if they can put up a good offensive performance in that stadium, I'd be impressed even if this isn't a vintage Minny defense.