i LOVE this role and it sounds super cool!! /support
love the whole doppelganger addition and is perfect since roles only occasionally get the Necronomicon so I don't think that it is op at all.
maybe taking away the element to talk isn't a horrible idea, but you could also do this:
create a 1 message per day limit where you can choose when to send the message but it has to be a limit of a certain number of characters, and there would obviously be a filter (stronger than the regular general chat filter possibly?).
You could even make it have a certain set of messages you can choose from and you can fill in names or numbers by selection, but this would require a special menu and would give away the presence of the Pythoness if anyone recognized the messages. though, most coven roles don't act without being noticed anyways. one way to avoid this though would be to randomize whatever messages the pythoness can select from so that every time someone plays the pythoness and uses a preset message, some people may recognize the message, and some may have never seen it before.
Though not having a free bar to type a message would void the ability to put out a false investigative result or false psychic's vision through the Doppelganger to convince the town to lynch someone.
I'm not sure if this will matter but take into account that The Necromonicon isn't accessible until night 3, and will in most cases take longer than that to get to the pythoness depending on how many coven members there are alive and is a Coven Leader is present. So doppelgangers will usually only be present in the last half of the game (considering most games are about 6-8 nights long)
Also, I have a question- would the Spy be able to see any interaction with the Pythoness and a Doppelganger? Obviously, they don't visit them at night but maybe it could count as a visit? or maybe if the spy bugged the doppelganger they would get a message the next day anytime the Pythoness controlls the doppelganger to talk or vote that "Your target was given an order from the Pythoness."
And if it ever comes to the point where the role is to OP in the forums a giant nerf would be to show the message that the Pythoness is whispering to the Doppelganger whenever they have them do an action.
Like "Dandelion is whispering to Bob Ross" (Dandelion being the Pythoness and Bob Ross being the Doppelganger) and seeing a vote or a message sent right after from Bob Ross might make people realize who the Pythoness is but that would somewhat of a lasrge nerf to their Necromonicon ability.
ANOTHER nerf would be for any investigation of the Doppelganger to be the result of the Pythoness or for the Consigliere to just straight up say "Your target seems to have lost their soul, they must be a Doppelganger!"
food for thought haha
I know this was a lot but I hope this helped in some way, shape, or form.