For nearly two years, I have been discussing with a nice JW lady over interpretation of biblical passages (we started with the divinity of Jesus Christ) and differences between JW and Catholic teachings. The divide is huge! In the beginning this lady seemed to have the upper hand during our sessions, armed with her Emphatic Diaglott and Kingdom Interlinear translator (pushed by the Watchtower of course). She used and freely provided attractively printed publications, e.g., What the Bible Really Teaches, and their periodic Awaken and Watchtower magazines. After I beefed up on the issue(s) involving a lot of effort and hours (including good research and pointers from CAF!), I have become more confident in discussing with said lady. I cross-checked NWT verses with those from KJV and Douay Rheims, keeping in mind the context of the passages. It is clear, as I pointed out to her, that the bible version used and touted by JWs as the “true” translation, contain multiple verses their translators changed to suit their theology. Never mind that NWT was only published in 1961 by translators who do not have solid Greek language credentials, offering no more than wooden literalism. Of course, JWs are bolstered by the praise Professor Jason Beduhn bestowed on their NWT version, even if his is a minority opinion among biblical scholars.
I know of no one personally who converted from Jehovahs to Catholic, but there is an organization of Catholics who were former Jehovahs Witnesses (see
www.catholicxjw.com). It seems that the more I read up on their organization, the more I feel that that the zeal of JWS including this lady, with whom I have discussions, deserves a better cause.
Indeed it is troubling that the faithful and aggressive door to door work/hours logged by current JWs result in big bumps in their new membership (it is now upwards of 7 million worldwide), mostly getting their converts from the Catholic and Protestant camps that are, you guessed it, not versed with the bible and not grounded in their faith. But Watchtower has lost scores from its own through the years, including JW elders, Pioneers, Bethelites, including a high ranking Governing Body member, Raymond Franz. The light did get brighter for them!
I hope sharing this helps with questions in the OP.
Among my prayers is a novena to St. Paul, the great Church doctor to the Gentiles and Apostle of conversion, to help enlighten my lady JW friend.
Blessings