This is the most successful clandestine operation by Russia against the U.S. in History

Unless you think the Kennedy assassination was a more successful clandestine operation by Russia than this one?

However, barring the assassination of JFK the disruption of the U.S. elections in favor of Trump is on a par I would say with their assassination of Kennedy in 1963.

This has already been said by CIA officials at least regarding the attempted corruption of the U.S. elections in favor of Trump.

So, will we have new elections because of bona fide harm to the electoral process?

I would say at this point it is more likely to be that the Electoral College likely might deny Trump the election and the House of Representatives likely would nominate either Romney or Ryan to be president or maybe Pence would be president and Hillary Clinton might be Vice President in this situation or something like this.

IF no candidate for president gets 270 electoral votes then the House of Representatives picks the President of the United States. So, it is possible it will be Romney, Ryan, Clinton or Pence would be the most likely choices of the House of Representatives.

Though Clinton won the most popular votes that isn't enough to make her president in this case, necessarily.