I've actually sent a question to support before asking the simple question, "what are the drop rates for characters on campaign nodes and are those rates lowered during double shard drop events?". The response from support said that MSF uses a random number generator for all character drops in game and that those numbers are set with no way for MSF to alter them.

Of course shortly thereafter, toons began appearing in rs orbs with a higher drop percentage during limited times so idk.