When I look at my stats for this game, I see that I'm 15% finished after 83 hours of play. The averages hover around 7% finished after 20 hours. Do you think any of these numbers is credible? If so, most players are a lot smarter than me but much more easily discouraged, which is not a good sign for the parties with financial interests in this game.

One thing I noticed was an awesome difficulty spike when I approached my first bronze seal. Playing on Settler difficulty, I was not struggling until I got to that point. Is this a potential problem for new players who may be less experienced with strategy games than the beta testers who have participated in the development process?

I wouldn't worry about this percentage. It's just the number of achievements you have unlocked, and not related to the level you reached or upgrades purchased in the Smoldering City.

I think the reason for the low playtime average is that it also counts players that have purchased the game but haven't played it yet (or played it offline or without time tracking).