Basically just start with what you're aiming to enable and work backwards (as you've started to do). With judicious use of grep find out where that symbol is defined. If it's in arch configs for other arches but not your own, it's probably that.
There may be better tools out there to do this, but in my experience just sleuthing it out a bit will answer your question. The Kconfig system can be complex, but the files are pretty readable.
Yeah, I was watching Potato McWhiskey and this is his take. They have metrics that show most people don't actually finish a game and that indicates a pretty big flaw in game design.
One interesting thing the devs brought up was the ability to pivot from one civ to another based on new information. Like if you discover your continent is mostly plains and horses, then maybe your next iteration looks more like the Mongols, with bonuses to cavalry. If your early conquest didn't go off, maybe you pivot to a more science or culture oriented civ.
I don't hate these ideas, it just depends on how it actually feels in game.