Terms such as mental illness and mental disorder are not precisely defined, and we doubt that they can be defined based on science alone.

That's putting it so diplomatically you should write it in French.

Mental illness and mental disorder are NOT defined AT ALL. Not just "not precizely" - not at all. And that is part of their purpoze: that they are slippery so they are unfalsifiable. Of course they are also not based on science and can never be: they are based on religion; although these days it is about the secular religions of the Mental Health establishment, Big Pharma, and Big Government through criminal law and the punitive state; rather than the pre-modern religions of Jesus, Muhammad or Krishna.