yeah, I think it is not possible to introduce it without breaking some things (array values for parameters are currently supported by entering them using the inline Yaml syntax when being asked for it)

If you start changing some deep nested array, it probably means you are setting the semantic configuration of bundles rather than setting parameters. And for this, a dedicated tool being aware of the config you are building will probably be a better job (a dist file will not be enough to describe a deep config in a way allowing to provide a good interactive builder)