Hi Cameyo 
Yes, we will (Whenever possible) keep full backward-compatibility with all of ZBrush resources ( Documents, Tools, Materials, Lights… as well as ZScripts).
If you have written a ZScript that executed properly in an earlier version of ZBrush but is not performing as expected in a newer version; you may be able to resolve the problem by simply adding a single [IConfig…] command to your script (preferably at the start of your script).
Example…
If you have manually written a ZScript that executes properly in version 1.51 but it fails to perform properly in a newer version, you may want to add the following command at the start of your ZScript
[IConfig,1.51]
As soon as this command is executed, ZBrush will (whenever possible) reconfigure itself to the specified ZScript-version.
You can verify that ZBrush has recognized your [IConfig…] command by looking at the ZBrush title bar… When a ZScript is running you’ll see the compatibility -version of the executed ZScript as … ZVer
1.51
A ZVer
? will be displayed when ZBrush can’t determine the ZScript compatibility-version.
Note: [IReset…] command executes a full ZBrush initialization to a specified compatibility-version. (this command is automatically included within each recorded ZScript )
In most case, adding the [IConfig…] (or the full [IReset…] ) command will allow the ZScript to behave as expected. If the ZScript still does not perform properly then it is probably relying on a ZBrush function that has been changed and the ZScript command will need to be adjusted.
If the above fails, Please email me your ZScript and I’ll try to find a solution to the problem.
Hope this helps 
-Pixolator
P.S. Try to include [IConfig…] (or [IReset…]) command in all of your ZScripts to allow future ZBrush versions to correctly interpret these scripts .