Translation:We will eat with my children and my friends before the concert tomorrow.
In the above sentence, the translation for clann is "children", so I think it's correct.
According to teanglann.ie, clann means offspring, and I rarely hear it used to mean "family". Teaghlach would generally mean household, which would be used in the context of a nuclear family. Muintir kinda means "folk" or "people". e.g. Mo mhuintir = my people.
Do you not understand that your children are, by definition, do chlann?
If you're happy with a google-translate level, béarlachas-style translation, go ahead and use páistí in this type of situation. But if you'd prefer a richer Irish, that recognizes that Irish is not English, and English is too impoverished a language to catch all of the nuances of Irish, then don't complain when Duolingo helps you to understand some of that saibhreas.