I don't think anyone in the history of forever has ever been tried for a Logan Act violation.
And so I went to look for the facts, and indeed, no one ever has been on trial for violating the Act which was enacted in 1799.
Only two indictments have ever been handed up under the Logan Act, both in the 19th century. The first occurred in 1803 when a grand jury indicted Francis Flournoy, a Kentucky farmer, who had written an article in the Frankfort Guardian of Freedom under the pen name of "A Western American". In the article, Flournoy advocated for the creation of a new independent state, not part of the US, in North America that would ally with France. The United States Attorney for Kentucky, an Adams appointee and brother-in-law of Chief Justice John Marshall, went no further than procuring the indictment of Flournoy, and there was no further prosecution of him. The purchase of the Louisiana Territory later that year appeared to cause the separatism issue to become moot, and the case was abandoned.[2]
In 1852, Jonas Phillips Levy became the second, and to date the last, person to be indicted under the Logan Act. Levy, an American merchant and sailor who was living in Mexico at the time, had acquired a grant to build a railway across the Isthmus of Tehuantepec, the narrowest point across Mexico. Secretary of State Daniel Webster had been pressuring Mexico to accept a treaty that would allow a different group of American businessmen to build the railway. Levy wrote a letter to Mexican President Mariano Arista urging him to reject Webster's proposed treaty, prompting Webster to seek an indictment against Levy for violating the Logan Act. Federal prosecutors were forced to dismiss the case after Arista refused to hand over the original copy of the letter, depriving them of the evidence they needed to convict Levy.[3]
Do the right thing. It will gratify some people and astonish the rest. - Mark Twain