For the murders in the 1990s at least it makes sense why he wasn't indicted. Mike Virgilio was identified as a shooter just as explicitly by Natale and wasn't indicted either.

The making ceremony is only evidence that the criminal enterprise exists. If they don't have any crimes to connect to Lancellotti (like the gambling, loan sharking, etc., acts against Grande or Mazzone) then there's no point in charging him. They need to prove that crimes being committed are linked to the organisation, not just that the organisation is there. If that was the case then it wouldn't just be Lancellotti but everyone else at that ceremony would've been indicted too (Ligambi, the Borgesis, Accardo, Johnny Chang...)

Unless Persiano caught Lancellotti at a later point on tape giving out loan shark money or accepting cash from extortions than I'm not expecting him to be charged in anything superseding. No-one in the indictment is just charged with being at the ceremony.