Some of the other states are system is not ready, temporarily not available, deactivated by the driver, ready (no warnings active), error, not available, LKA suppressed by operator behavior (like turn signal).
>> "System is actuating" means that it is getting ready to work
Shouldn't "getting ready to work" be "system is ready" state?
I really don't know. I would have expected there to be some state that says the system is in the process of initiating and should be ready soon, however that might well be "not ready". It could be that "System is actuating" may mean that a warning is being shown to the driver, or that a steering force is being asked for by the system.
In the end all the states are just names. The engineers who design the system agree on a set of behaviours that depend on a number of states, and often give those states names. The subtlety behind those states may be far more complicated than can be described in a few words.
The databases for CAN signals are often limited to quite short names for states. There may also be a load of comments that describe in detail what the signals mean, but those will probably be in separate documents, and not in the database.
For example, a lot of cars have a signal called "Power Mode", with states of "Key out", "Aux", "Ignition on", "Engine running" and "Crank". Maybe 20 years ago, those meant what they said. Nowadays they don't. There is no key to take out. A car can have the engine running to get the cabin hot or cold ready for the driver, but the Power Mode says that the state is "Key out". When the engine stops to save fuel at traffic lights, the Power Mode is still "Engine running", so that the instruments still work. When the lights change and the driver accelerates, the Power Mode doesn't go to "Crank", even though the starter motor operates, because in "Crank" mode, the radio might turn off.
Electric cars still emulate all those modes, even though there is no physical difference between any of them until the car is put into gear and the brake released.