Just because God asked Israel to make cherubim’s in His temple, doesn't mean the second commandment is null and void. They were not bowing to the cherubim's, they were bowing to God, specifically the Ark of the Covenant which the cherubim were also glorifying by being depicted as bowing down to Him and covering Him with their wings just as they do in heaven. Not to mention the Lord God explicitly commanded them to make the cherubim. This is very different to making carved and molten idols and depictions that you directly bow down to and worship. Last I checked God didn't command you to make your best depiction of Jesus Christ with long womanly flowing hair, or to put an image of a dead saint in your car for protection. He commanded you not to do such things.