Toml is great for simple use-cases. For complex ones you have the same problem that yaml has: Templating a language with significant whitespace via text substitution is a horrible horrible idea. Somehow this sad state of affairs has become industry standard.
Its not even the white space, a food liter or language server can handle that. It's not that, as much ad the fact that the most complex data structure is a list.
If you want to get crazy, you can push a dict into a list and operated on it but it gets tough at the second level. And don't get me started on if/else statements.
