So I tried this, and it didn't make any difference in AI preference... they built no housing throughout ancient and classical periods . My additions show up in the DB, so either I committed some other oversight, or housing doesn't have any weight in the calculation like I thought it might. They do build granaries like they're going out of style in vanilla, so who knows?
Without starting a new game, I made some small changes to yields, adding +1 production to ancient lower housing, and +1 food to only the first level of middle class. That got the ball rolling, and AI cities quickly built lower and middle housing levels, with rising populations. What was interesting here is that they continued to build the variants to which I hadn't assigned extra yields. So the early instances would seem to be a good leverage point to get things started, without inflating overall yields. Unfortunately, it makes little gameplay sense (IMHO) to hand out additional yields for only a subset of early housing. I guess if this method is to be used, it might be best to stick with food as the "carrot", since that has less balance considerations. I'll try strictly food next time... it did work for middle class.
I also looked more at how pseudo-yields function, but there are no buildings that utilize that, nor is it in the schema for the buildings table.
EDIT: Other notes: Tercio desync seems fixed... Naval upgrade chain to caravel is working... Knights still do that looped downgrade to Horseman and back
