Becoming enlightened does not mean you lose your perceptions(Sanna) of conventional reality.
The Buddha himself used the words 'I', "I am", 'Ananda', Sariputta' etc. Sakkaya Ditthi is taking up a view that the five aggregates is a self. You do not need to take up a view to perceive conventional realities.
Enlightened beings do chant. If you read the Ratana Sutta, you will see the Buddha himself did that and also instructed venerable Ananada to sprinkle Paritta water. The difference is that enlightened beings do not cling to rights and rituals. They do not take up views that rights and rituals are the way to end suffering.
The Arahanth chief disciples and other enlightened beings bowed down to the Buddha. Enlightenment does not take away your sense of respect and gratitude.
But if you hear someone saying that what the Buddha preached is wrong, that person is definitely not enlightened.
Those days, the Buddha himself would look into the person's mind and see if he or she is enlightened. The Arahaths with psychic powers and angels would also look into the minds of meditators to see their progress. Apart from that, a very experienced meditation teacher would be able to make an educated guess on the progress of the student/follower.