If your environment is MS Win, may I please have more detail on how you threw out Citrix. Guacamole is not providing multiple sessions to a single computer, rather that's the functionality of a broker such as Microsoft Terminal Server (termdd.sys) which allows for multiple sessions connected to the console of a computer, likewise for Citrix. For your 50+ engineers to work remotely, they would have had to have been connected to 50 unique computers via the Guacamole Server, or you still have a Citrix server and Guacamole has replaced the Citrix ICA client...
[The web application deployed to the Guacamole server reads the Guacamole protocol and forwards it to guacd, the native Guacamole proxy. This proxy actually interprets the contents of the Guacamole protocol, connecting to any number of remote desktop servers on behalf of the user.|https://guacamole.incubator.apache.org/doc/gug/guacamole-arc...]