No idea if this will help anyone but what fixed my problem (corn and cucumber not working and toast/scones resetting sims), along with removing all the fix files except oldmill+wowonder, was making sure a fresh copy of the ccmerged file was in my overrides folder as well as the DCBackup one. I had, for some reason, deleted the ccmerged file from my overrides altogether but placing the up to date one in there fixed my problem.
Does all the previous content that needed fixes still work?
Ah, my bad, I meant all the fixes concerning the old mill set (cuke_corn fix, canning_tea-fixes etc) But yes everything else still works.
Looking back at my file set up it seems I do have those mill set fixes installed in my packages folder but I'm not sure if they are necessary. All I know is that making sure copies of the up to date ccmerged file are in all of these folders seems to have fixed my problems.