I read something about Carter Page possibly taking legal action but there were no particulars.
A civil suit may do more damage in the long run. Hit them in their wallets, tie their assets up in protracted litigation. Their assists can be frozen prior to trial if plaintiffs lawyers can convince the court that the defendants are flight risks, which they are.
Defendants will *try* to claim immunity as government employees acting in the scope of employment. But, this is so far outside the normal scope, so unreasonable, so unconscionable, that I think that defense would fail.
The biggest challenge would be finding impartial judges and/or jurors.