If the elders did something wrong or bad, can the younger ones tell them?

You can’t say it in person or you have to say it tactfully.

Depending on the occasion, there are things to talk about. It's okay to occasionally interrupt and say something, but if that matter will offend the elders, then it's best not to say it, or say it in private. Otherwise, people around you will only think you are rude and will not think you are explaining.

Of course, if the elders go astray, they will definitely stop them.