Vanilla general "recruitment" is still there, i must confirm that, and also i have problems to get the named generals (Union campaign) available, sometimes it works, sometimes not, where i get max the first 2 of the named generals. The scripting.lua seems here not to fire properly, but comicably it works with the named generals for the AI (CSA, when i play Union).
As for the file db agent_spawnings table, the value 0 is vanilla default value, afaik, the value 0 there does not mean, that generals won't be spawned, it is just a base value, for generals at least, i guess. I think the only thing that helps here, is to use the units table and put in ie. europe region resource for them, and/or list them for every participating faction in the unit_permission tables - i did this (permission table), and ie. the permission table alone does not prevent CSA AI from getting a vanilla general, so perhaps the region resource is the only way to get them out, but possibly also this won't work, as generals are just basic agent characters, not bodyguard units alone as listed in units table (however, i'll try this still).