Hi,
I'm the developer of Ovale Spell Priority. There are over 75K lines of code and I found that it was not manageable anymore to develop with Lua. As I use Typescript at work, I wanted to leverage these skills and use it for my addons development and I created tstolua three years ago. It's a Typescript to Lua 5.1 compiler that works with World of Warcraft (it uses LibStub to manage modules).
If you are interested this is the Github of Ovale:
https://github.com/Sidoine/Ovale
And the Github of tstolua:
https://github.com/wowts/tstolua
I think that tstolua starts to be mature enough if somebody wants to try it for its own addons. Before I dedicate time to document everything, I would like to know if somebody is interested.