Is the hadith: “Enjoin good, even if you do not do it; and forbid evil, even if you do not abstain from it” authentic, and how does it reconcile with the stern warning for those who enjoin good but do not do it, and forbid evil but commit it?

The Hadith was narrated by Al-Tabarani with a weak wording, but its meaning is the obligation to denounce evil even if the one forbidding it falls into it. This is because enjoining good and forbidding evil is an obligation, and abandoning evil is an obligation. The obligation of one does not negate the other.