Not sure if you looked at your IOReg file, but your SMBIos shows Optiplex 3070 instead of iMac19,1 you try to emulate. Don't know if that could be the issue but it's worth looking into.
Looking at your config file, I see you have UpdateSMBIOSMode set to custom which is fine, but you need CustomSMBIOSGuid enabled as well. They both must be paired correctly. You currently have it disabled. If you want it disabled, then you'll need to set UpdateSMBIOSMode to create. Go with the 1st option.
Fix that and see if it makes a difference and we'll go from there.