Terminal 2G is a stand-alone building, and is used for commuter airplanes only.
From your arrival terminal 2E, you'll need to walk, then take a tram ride (follow the 2G direction sign), then walk, then eventually go outside of the building, take a shuttle bus at the curb to reach terminal 2G building.
You don't need to be able to speak French, just ask any uniformed airline employee at the airport, 'Which way to Terminal 2G?" they will point to you where to take the shuttle bus. As long as you understand that you'll need to go outside of the building to get on a shuttle bus to reach terminal 2G building, that is a big help already.
I was at CDG this May, and like you, I had to go from terminal 2E to 2G. I had 1 hour and 55 minutes in between flights, and I made it in about 1 hour and 20 minutes. We could not board our commuter airplane until about 5 minutes before flight time, so we had about 20 minutes to catch our breath at the seating area in 2G.
With 1 hour and 40 minutes I think you can make it, but if it worries you, then you should call GCT to request a different route.