Hi there, and thanks for the kind words!
I don't think there's any easy way to learn it, other than try and look at existing code and learn from it.
It's mostly experience and messing around with it for a long time. As a side note, Ren'py (fairly) recently did update their documentation to be more thorough - so if you haven't looked at it recently I'd recommend that!
I think the best advise I have to offer is "how to ask a programming question" - meaning don't ask about your exact problem if you're stuck, ask about what you're trying to achieve, your end goal. This goes for when you get stuck in whatever you're doing for yourself as well, there's likely another angle to achieve the same thing that might make more sense, especially so in Ren'py.
I'll see about uploading some more details about stuff I've done to DT the closer I get to releasing the game. Aside from that, if you get stuck and have any questions - feel free to DM me. Most easily reached through twitter or discord.
/Grunt