I fear that the information you're looking for does not exist. It's hard to prove a negative, admittedly, but I've never seen or heard of such information, and I imagine that something that comes up so often would have to be located somewhere easy to find. Since it apparently isn't, I'm fairly confident that the information does not exist in any Paizo publication.
I can't say for sure why such information wouldn't exist without engaging in speculation and guesswork - But I'd like to think that my guesswork isn't too far off, so here it is:
The sad truth is that most GMs don't know a lot about architecture. I mean sure, if they've actually studied architectural history, they'll know the difference between Doric and Corinthian columns, and the different styles of architrave, and the kinds of floorplans that were popular in fifteenth-century italian city-states.
But even if they do know, chances are their players won't. As a result, all that knowledge will likely go to waste - because if you were to rank the things players need to know about a dungeon, your list would start with things like:
- Where the entrances are
- Where the loot is
- Where the monster lairs are located
- Where the Mcguffin might be found
And so on. The actual details of the architectural style will be so far down such a list that that most groups will never get to them beyond the most superficial level they need to make decisions - and that means that detailing architectural styles is similarly low on the priority lists of campaign setting writers.
"But wait," I hear you thinking, "What about flavour? Flavour's important, and the look of a building is an important part of that!" Well, you're right, but again, most players and GMs aren't familiar enough with architectural terminology for an accurate and detailed description to make much sense - so beyond vague descriptions like "Airy, soaring archways" and "oppressive and dark stone passageways" you're not going to find many useful descriptions of architecture that you'll be able to use, and even those are in the text of adventures rather than in some convenient Pathfinder Campaign Setting supplement.
Even illustrations from published adventures won't help us; The artists who draw them have as much information about late third-era dwarven burrow construction as we do; Every artist will draw their own impression of the architectural style in question, and there's little consistency to be found.
Finally, even in the few situations where it comes up, published information on architecture styles is unnecessary. Most GMs are content with the (completely non-existent) information that's already available, because they know they can just make up the details of fictional art, architecture and cuisine as the campaign demands. Such details are vanishingly unlikely to be important, so few problems will ever be caused by their fabrication; And players won't call their GMs out for getting details wrong, since there's no cannon sources to contradict.