Scriptural Authenticity

You may be able to verify the authenticity of the sutras, whether they are spoken by the Buddha or not. But you have to authenticate the Truth in the Buddha's words by yourself. In this sense, it all boils down to you to develop wisdom to discern what is true, to continually increase your wisdom to realise the total Truth. In this sense, there is no need to argue on scriptural authority- since the ultimate authority is you. Improve this authority ultimately instead. The Buddha's onus was in sharing His Enlightenment. Discovering the Truth in it is your onus. Discovering its reality is your bonus.