Returning escaped slaves was in the constitution itself (fugitive slave clause).
Founders’ intent is pretty irrelevant to today’s problems. They ran forced labor plantations, hadn’t mastered electricity or germ theory of disease, and the biggest city was ~30K people.
1 person = 1 vote, get rid of all the rural planter rigs.
States are artificial, national elections should be ranked choice, or at worst simple majority vote.
Electoral college was a sop to slavers and should be deleted. It doesn't empower small states, it empowers large states which happen to be swing states.
Criminal impunity for political elites backstops their entire racket: laundering hard bribes into soft, insider trading and so on. They've blocked T•••• prosecution for things like the coup because federal law enforcement report to them, and they're wedded to the immunity. Only the most egregious get prosecuted, e.g. the Congressman insider-trading on the phone in the background of a public T•••• event.
The opposite — the US constitution is more like a slaver bill of rights, rife with plantation oligarch backdoors. The checks and balances are akin to NBA owners negotiating how not to ruin each other. Those rights originally were only extended to white men formally, and only rich white men in effect.