In your code change “number” to “bool”. You can leave the datatype as float64. Then you should get a 0.000000000 for FALSE and 1.0000000000 for true.
What helps a lot is to launch the SimvarWatcher app. It is in the “MSFS SDK folder” → Samples → SimvarWatcher → bin → x64 → Release (or Debug). It should be Simvars.exe
If it is not there you might have to build it in Visual Studio.