IMHO, having typings in your .script and .gui_script is mostly a requirement for a project of any decent size. A significant amount of source code lives in those files, and you still want type safety when interacting with your lua modules.
I tried to adopt TL at one point and this was a major blocker for me. The other was LSP integration in the editor but that’s been added recently, which made me interested again. But this remaining issue is kind of a showstopper for me personally.
ts-defold has a fairly decent solution for dealing with this. It just strips the .lua extension if the file extension is .script or .gui_script.
So you have a file named player.script.tl and you end up with a file player.script