What do you mean script editor in VS doesn't have color change? It has color syntax highlighting for Lua.
What I mentioned is the only possible method currently of debugging externally.
Personally I just write my scripts in Sublime without debugging. I write based on my knowledge & by eye. If something returns an error in the log when I try running the script then I check around the line number it mentions & try to figure out what's causing the error based on the error message & what I can see.
You can write scripts externally in sublime text, if you like by saving a .lua file & then writing a small function
inside of vs script editor to load (include) the .lua file on game launch. This will not however give you debug capabilities like the zerobrane app with remote access, like I mentioned in my last post, but it's a nice alternative to writing your scripts inside of VS.