The abstract noun "faithfulness" can be stated as "faithfully" or "faithful." See how you translated a similar phrase in [Exodus 20:6](../20/06.md). Alternate translation: "faithfully loving thousands of generations" or "faithful to his covenant with thousands of generation" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])
Punishing people is spoken of as if punishment were an object that someone could bring on people. Alternate translation: "He will punish the children for their fathers' sin" (See: [[rc://en/ta/man/translate/figs-metaphor]])