I'm not a conspiracy theorist by nature. I believe Lee Harvey Oswald acted alone. 9/11 wasn't an inside job. The Earth is round.
That being said, I have a very difficult time accepting the JW numbers at face value. The reason for this is that Watchtower leadership believes they're entitled to lie to protect the Watchtower's interests. We saw this with the ARC. I read a news article about shunning not long ago where a WT representative outright lied in a way I don't ever recall them lying. Not clever word play. Not half truths intended to convey an incorrect impression. Lies.
It stems from their interpretation of the Rahab account. Apparently Rahab was authorized to lie because the Philistines didn't "deserve the truth." If leadership believes the flock might stumble if they publish negative growth numbers, I don't think they'd hesitate to pad them.