You want genuine growth? In Europe, America, and Australia, this is not going to do the job. Altering these "a generation" is not going to keep people in those lands active. And without this, where are they going to come up with money and missionaries to send to Africa so they can keep those numbers propped up?
You might get people in parts of the world where ignorance is supreme with this. Try this in Nigeria, Cameroon, The Congo, Burundi, and the areas surrounding this, and most people there will fall for it. But, who is going to be willing to help if they realize the whole jokehovian system is bogus? No one is going to learn to speak French (much of Africa is French speaking) or Spanish (as in Latin America), suffer the hardships, and do all that hard work for a bad religion where they can't even keep the narrative straight.
Not to mention the persecution. Last I knew, the work is banned in Burundi (besides, anyone interested in missionary work there needs to become fluent in French). What other countries will be next? And, even where it is legal, you get tribal persecution--and who wants to learn those languages? All for a religion where "the truth" keeps being altered like this.
Sure, they might see growth there. But without missionaries, those congregations will be left to flounder. Not to mention, there is no money coming from America or Europe--there goes the means to spread more of those worthless bibles in the Third World.