Anastasia, since you are interested in the legal ramifications of calling someone a charlatan, I thought that I might provide for you the legal definition of such:
Charlatan. One who pretends to more knowledge or skill than he possesses; a quack; a faker. - BLACKS LAW DICTIONARY page 213 edition of 1979
"True, it is expecting great things to claim, as we do, that within the coming twenty-six years all present governments will be overthrown and dissolved." "In view of this strong Bible evidence concerning the Times of the Gentiles, we consider it an established truth that the final end of the kingdoms of this world, and the full establishment of the Kingdom of God will be accomplished near the end of AD1915." - Study IV The Times Of The Gentiles in the publication THE TIME IS AT HAND 1889 edition written by Pastor Russell
Since these direct statement never came true and the governments of the earth have not been dissolved, in the legal sense it would seem that Pastor Russell was indeed a CHARLATAN.
Since what he prophesied did not come true, he was also propagating LIES; albeit not in the strictest legal sense.