If you're confused about 'traditional colour theory', there's a newly published paper that clearly describes this branch of colour theory. Published in the leading journal on colour (Color Research & Application) the paper avoids confusing and conflated ideas about colour, making this branch of colour theory and application easy to understand.
Written by Dr Zena O'Connor (whose PhD focused on responses to colour in the built environment), this peer-reviewed paper can be accessed online.
Abstract - Traditional colour theory: A review (Color Research & Application, 2021)
A plethora of colour theories exist in the literature across diverse fields of inquiry including physics, phenomenology, psychology, linguistics, vision science, art, and design. In addition, colour theories abound in mainstream media and the internet. One particular branch of these diverse colour theories is referred to as ‘traditional colour theory’ and this branch is distinguished from other branches of colour theory by its ontological focus, epistemological traditions and characteristics, and its applications in art, applied design and design of the built environment. This branch of theory, which dates back some centuries and has a record of contribution, has also received criticism primarily due to an inadequate correspondence with the science of colour and the simplistic nature of conceptual models and constructs associated with this branch of colour theory.
This discussion reviews the aims and intentions of traditional colour theory gleaned from key colour theorists. Reference is made to the ontological focus and epistemological traditions and methods evident in this branch of colour theory plus its validity primarily in respect to applied design and design of the built environment. A definition of traditional colour theory is offered and criticism of this branch of colour theory is addressed in conjunction with elucidation of its legacy.