The documentation has been historically bad at separating what is possible from a scripting perspective in Android Enterprise vs. Android+ however they have taken steps more recently to help split this apart:

https://www.soti.net/mc/help/v15.2/en/scriptcmds/reference/androidplus_enterprise_do.html

Note that your specific request around writesecuresetting is a particularly sour point amongst the community. This is apparently something that could be supported but Zebra is no longer signing the plugins required in order for this privilege to be adequately granted on the devices and so it is not officially supported any more. You can sometimes get this permission manually granted on the devices but then only certain subsets of the configurations seem to work and it is more of a guessing game to figure out which ones work and which ones don't. This limitation is apparently not there for Honeywell and other device manufacturers and it seems to be specific to the Zebra Android Enterprise devices managed in SOTI due to the strategic direction toward OEM exposed configurations like MX and OEMConfig.

Zebra is slowly adding some of the most requested writesecuresetting options to MX, but there are still a considerable amount of feature gaps. We only just recently got Orientation/Rotation control for instance. 

Here is another thread to give you some context:

https://discussions.soti.net/thread/wish-list-for-zebra-ae-functionality/

Hi Farid

Historically, many of the new script commands in Android+ platform were added to fix problems for specific OEM brand.  Hence the many script commands and their supported arguments can be specific to particular brand.  I believe some were not included in the  online documentation because they were too specifc to particular devices and were therefore revealed to customers on a need basis.  This likely helped to reduce unnecessary support effort, and customers will not get disappointed if they found out that many of the script commands did not work on their device brands/models or for their device agent versions.  What worked or not depended both on the specific device agent as well as the firmware on the device.   

The script command writesecuresetting has actually been supported only in a VERY VERY SMALL percentage of the 100+ device brands with Android+ device agent.   For Android Enteprise platform, Google has been rolling out standards related to MDM/EMM api on device settings for compliant devices, and I believe that will be more consistent (i.e. in terms of the arguments and syntax) support on wider range of devices in the future.  However,  as many options defined by Google are not mandatory features,  it is still up to the OEM device firmware developers and their management, not any MDM/EMM vendor such as Soti, to decide whether a particular optional feature is supported or not. 

So, as Matt said in his post,  it can be a guessing game.  If your company definitely needs a partcular set of coomands to work for a new project,  do thorough tests before purchasing the devices to be used.  For project legacy or BYOD devices, one has to live with what are there on the device, and closely monitor the ever-changing developements an API standards set by Google for different AE device modes.

As I am not not from Soti, Google or any OEM device brand, I do not represent them, and all the above are my personal views.