I was honestly just going to fiddle with the formula and see how various trial saves came through - I'm planning on using CK2 to cover approx 300-900AD in my megacampaign via bashing it together with WTWSMS, so was initially going to try keeping holding slots the same but tripling or quadrupling the thresholds for prebuilt holdings.
Java's beyond my skillset, but I have been making some tweaks to the converted cultures and making cultural buildings/retinues. Some are somewhat save-specific (moved Wusun to a 'West Sinic' group after they migrated to Poland), but most are just for common converter cultures - Punic, continental celtic, etc. Will upload those once I've gone through the cultures.