What you are observing is correct. In the example image below, when the vehicle reaches 2G of braking force, the G-Belt will be at 100% of it's possible travel. If you move the intensity slider to 50%, then at 2G, the G-Belt would be at 50% of its possible travel.

The 2G is filled in by cloud tuning. It's an accurate value that can be achieved with that vehicle on that track. Therefore it is the maximum that we scale to in order to prevent the problem of clipping which is another topic. For the purpose of this explanation, suffice it to say, if we set the value lower than what the vehicle actually could achieve, lets say 1.5G, we could experience the problem of clipping at times, which is an undesirable feeling. Cloud tuning aims for accuracy and will avoid clipping by default.

Cloud tuning will never change the intensity values in your profile. Those are considered "user preference". We have solid defaults that are set the way they are for good reason, namely the way that the tire traction circle works, but you are free to change those intensity values and cloud tuning won't alter your preference. This is explained in more detail here: https://www.simxperience.com/slides/slide/what-does-cloud-tuning-do-77

Now, here is where it get's even more interesting. Let's say that for some reason, you're unable to drive the vehicle within 50% of its capability and that when you drive, the max braking force that you can achieve is really more like 1G. You could set your intensity slider to 200% which is basically doubling the output. That would in effect be the same thing as having lowered the G-Force value to 1G. Don't forget, we won't alter your intensity preference, so that 200% setting will stay the next time that cloud tuning fills in a G value for you.