While my overall goals are different, it seems as far as fixing Renewal mistakes go, it's the same as yours.
Not sure if it's any help but this is my server side repository : https://github.com/SeravySensei/rathena https://github.com/SeravySensei/rathena/commits/master
My plan is to make a single player server people can download and play on their own computer easily, one that offers balanced and enjoyable PvM gameplay, and server side AI allowing players to still play in parties despite having no actual human players to party with. I expect it'll take a year to dig through all the items, scripts, classes, skills, etc and fix them all but I am making good progress.