I learned TTAT while still serving as an elder, and served an additional year after that before resigning. During that time I served on several JCs. Here's where I did some damage according to the Watchtower. I got the accused off with reduced sentences (mild private reproof) instead of Puplic Reproof or DF. On another JC where the person was accused of apostasy, I grilled the accusers until they admitted that they might have misunderstood what the person said. The case was dropped and the person got off for the time being.
Teaching TTAT from the platform is very difficult. Here the best I was able to do was point out in a sly way, the flaws of the NWT in comparison to modern English translations like the TEV and the NAB.
As far as my JC work, the persons who got off with mild private reproof, are probably still in. Regarding the person accused of apostasy, a year after I left the BOE formed another JC and DFd her.
In my experience it is impossible to reform the JW organization from within. It's more likely that reform will come from without, due to law suits and government actions that threaten the Watchtower's financial assets.