There's a lot of fraud, waste,a abuse, or other chicanery in the courts and luckily in my experience they're never simply kept hidden without anyone noticing. The problem is always redressability. So much of the system requires discretionary rulings but the laws that dictate how we handle misconduct is heavily skewed in favor of the state if they ar a party and fails to take into account the urgency in resolving these cases that very often it becomes obvious that there's fraud, yes, but there's no redressability, and therefore there's no real punishment.
A particularly egregious case of falsifying evidence and using prtextual reasons to elicit false testimony and racially-based jury selections is the US v. Flowers case in the Supreme Court last term. There's a podcast on it, but the decision itself is... excoriating to say the least as to how far and how egregious the conduct was to try to execute an innocent man. It's discovered all right, but there's no punishment. So courts can and do definitely figure out fraud pretty readily, but when it comes to doing anything about it, victims not on the side of the state frequently find it cold comfort.