Ethan on 05 Jul, 2020 10:23 PM
We're actually in the process of updating this for the next release. If you want to try the latest preview version (http://infinitekind.com/preview), you'll see in the custom theme preferences that a lot of those cryptic terms now have a more detailed description about what they actually represent.
I notice in the latest preview build there are quite a lot of colour blocks in the custom theme area but there is no text along side them to indicate what they are. These seem to be some of the more cryptic ones that had text in MD2019 but I could not work out what they did.