I hold the Suttanta Pitaka: Digha Nikaya, Majjhima Nikaya, Anguttara Nikaya, and Samyutta Nikaya as authentic texts that handed to later generations via Bhante Ananda Arahanta Thera. So no doubt, these texts are of supreme authority in Buddhism.
Khuddaka Nikaya is a mixed bag but scholars often accept that several books in it are authentic such as Dhammapada, Itivuttaka, Theragatha, Therigatha, Udana, and Sutta Nipata, from the first council.
Later books such as Buddhavamsa and Patisambhidamagga are compiled by later monks in a helpful way to serve as a written record, as a source of inspiration, or to appreciate the complex doctrinal aspects of Dhamma. So these books are well orthodox in term of the Dhamma.
The Abhidhamma Pitaka exists after the first council were included in the scriptures and formed the Tipitaka. Since this Pitaka was scrutinized and accepted by the Arahantas of that time and later, I too accept it as orthodox scriptures.
Books like Visuddhimagga and all other commentaries, I treat these books similar to I treat the dhamma books cautiously. I only accept those commentaries from Mahaviharavins of Vibhajjavada tradition, that founded by Arahant Mahinda Thera.
The Abhidhamma Pitaka should not be the focus of Dhamma, despite its usefulness in Dhamma learning. The Suttanta Pitaka is complete and well-expounded. But people nowadays will interpret the Suttas in many ways to suit his/her agenda, creating a lot of wild theories and speculations. Therefore, the commentaries from Arahantas and ancient Elders are important to bring out true meanings and definition.