The Carrionette listed in Van Richten's Guide To Ravenloft, is given a Challenge Rating 1 (!?!) and features a pair of actions which seem very powerful:
Silver Needle. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 1 piercing damage plus 3 (1d6) necrotic damage, and the target must succeed on a DC 12 Charisma saving throw or become cursed for 1 minute. While cursed in this way, the target's speed is reduced by 10 feet, and it must roll a 1d4 and subtract the number rolled from each ability check or attack roll it makes.
Soul Swap. The carrionette targets a creature it can see within 15 feet of it that is cursed by its Silver Needle. Unless the target is protected by a protection from evil and good spell, it must succeed on a DC 12 Charisma saving throw or have its consciousness swapped with the carrionette. The carrionette gains control of the target's body, and the target is unconscious for 1 hour, after which it gains control of the carrionette's body. While controlling the target's body, the carrionette retains its Intelligence, Wisdom, and Charisma scores. It otherwise uses the controlled body's statistics, but doesn't gain access to the target's knowledge, class features, or proficiencies.
If the carrionette's body is destroyed, both the carrionette and the target die. A protection from evil and good spell cast on the controlled body drives the carrionette out and returns the consciousness of both creatures to their original bodies. The swap is also undone if the controlled body takes damage from the carrionette's Silver Needle.
This action's description says the carrionette uses the controlled body's statistics, but doesn't get the target's knowledge, class features, proficiencies, or mental (spellcasting) ability scores.
Please note that it doesn't say that the victim has any change in stats. It says the victim "gains control of the carrionette's body", but it makes no mention whether the victim's physical stats change the way the carrionette's do.
If the victims retain their own stats, they will not have resistance to Poison while in the carrionette's doll body, nor the benefit of its AC (gonna need it, with no armor on), nor will they be sustained by the wooden body's Unusual Nature. This will actually be very problematic for the carrionette, as the carrionette dies if its victim dies in the carrionette's body.
If the victim does get the carrionette's physical stats when it gains control of the Small construct's body, which stats does it get? (Does it get 15 AC? Or 13 AC? Does it get Unusual Nature? False Object?)
Most crucially (I think), is the carrionette's victim able to use either the Silver Needle or the Soul Swap actions?
Which of a carrionette victim's stats are changed (if any), while they are control of the carrionette body?