Those links remind me a lot of the process I went through trying to get a line on my tumblers. That Clichy did some version in the 1870s seems quite viable. Glassworks where very keen on what other companies were doing and what was selling. A very competitive business to be in at the time, especially given the the importation of glass from other countries.
Interestingly, Frederick Carder also developed a different process while at Stevens & Williams c.1890s Where the background on a cameo object would be "pecked" using a steel stylus powered by a sewing machine mechanism. Only a few pieces made due to breakage.