(just a disclaimer, I'm a masters student currently pursuing a degree in film studies. I'm not flaired as I don't see many film history questions here, but one of my specialties is early film history).

That signature generally served as a watermark for Griffith's films. Theft and espionage were common practices in the early years of film as no regulatory body or industry-wide organization had yet to be formed. Studios often inserted their logo within a scene as a type of watermark to ensure viewers and theater owners that they were getting a film made by them ([Here's] (https://alexonfilm.files.wordpress.com/2014/12/housewithshuttered2.jpg?w=625) an example of Biograph Studios, the studio Griffith worked for prior to striking out on his own, inserting their logo directly into the shot of a film). It has become difficult for historians to figure out exactly who made what film in the early history of the medium precisely because of the amount of theft and imitation that went on between studios. Allison McMahan covered this topic extensively in her book, Alice Guy Blanche: Lost Visionary of the Cinema which discusses the erasure of Alice Guy Blanche, who was one of the first directors to develop the concept of narrative film but has been lost to history due to the industrial theft and espionage characteristic of early film.

To add, what about translations?