They're required to disclose the trades, but usually have like 2 months to do it and the fines for not disclosing or improperly disclosing are minimal to none. It's a joke.

They should be held accountable like most people that have a conflict of interest. I work for a publicly traded company, and even though I don't have anything to do with the financial side of things, I'm forbidden from trading for most of the year to avoid any potential conflict of interest.

Not an index fund, but you can programmatically get access to their disclosed trades and create your own trading bot from there. I think this disclosures are a month or so after the fact.

https://api.quiverquant.com/docs/

I remember a thread on this a few months back, and the problem is that most of these trades happen at the small windows in time where members of congress have information the public doesn't. While trades by members of congress have to be made public, there is a delay. If you buy/sell after the delay (up to 45 days), the performance isn't really going to correlate with what they're getting.

Side effect would be that this would help them make even more money, due to lots of money following their trades after they have entered the position, and it would create pump and dump incentives.