I don’t see evidence or any particular reason for thinking Watchtower have hired “consultants”. What they do have are lots of lawyers and they do listen to their lawyers. It is possible that lawyers have given advice about the impact of shunning practices and it is possible that they’ve taken this on board.
A good source on the historical impact of legal challenges on Watchtower decision making and orientation is the following.
Côté, P., & Richardson, J. T. (2001). Disciplined litigation, vigilant litigation, and deformation: Dramatic organization change in Jehovah's Witnesses. Journal for the Scientific Study of Religion, 40(1), 11-25.
This is available free online if you search for it.
Senior sociologist Rodney Stark wrote a widely cited article on factors promoting the growth of religious groups focussing on JWs.
Stark, R., & Iannaccone, L. R. (1997). Why the Jehovah's Witnesses grow so rapidly: A theoretical application. Journal of contemporary Religion, 12(2), 133-157.
Also available free online.
An excellent new book discusses the impact of technological change on the way Jehovah’s Witnesses organise their congregational and preaching activities.
Rota, A. (2023). Collective intentionality and the study of religion: social ontology and empirical research (p. 280). Bloomsbury Academic.
Again, the pdf of this book is available free online if you search for it.
An older article that compared the sectarian character of JWs with the ‘denominationalizing’ trajectory of Seventh-day Adventists is the following.
Lawson, R. (1995). Sect-state relations: Accounting for the differing trajectories of Seventh-day Adventists and Jehovah's Witnesses. Sociology of Religion, 56(4), 351-377.
This article is interesting because 30 years later it’s worth considering whether JWs are beginning to alter their trajectory.
Another article compared external versus internal factors affecting growth.
Sturgis, P. W. (2008). Institutional versus Contextual Explanations for the Growth of the Jehovah's Witnesses in the United States, 1945-2002. Review of religious research, 290-300.
This article is not readily available but I can send it by email if you are interested.