Obviously, there is danger of illusion in these visions, locutions, and inner lights. No man is more suspicious of such things than the average Catholic priest.
Catholic faith stands clear of private revelations.
Such are not the ordinary channels whereby God teaches His mysteries to men. The ordinary channel is the Word Incarnate and His living Church on earth, a visible external authority. Certainly, every Christian man has his 'inner light,' but that light is none other than the grace of faith, enabling him and prompting him to believe, as on God's word, what the Church teaches him as revealed in Christ.