There is no way to work with the transparency mask in the Script SDK. This is the least of the problems. But when creating scripts to modify objects with masks, developers expect masks to be modified along with the parent object. After all, we see the "Linked to Art" icon in the Transparency panel.
But what we have all these years as script developers: resize(), position, translate() modify the object, and its mask remains as it was.
I've counted about 10 of my own scripts that use similar commands. I also have a large collection of other developers' scripts, where about 70 scripts contain similar commands. So none of them will help users automate operations with their art.
More than once I've had users come to me and ask, "Where did the opacity mask go after I ran the script? The only solution is to add dynamic actions with Move, Scale with calling app.doScript(). But this introduces many other problems and inconveniences.
Sergey Osokin commented
Of course, there are similar problems when using resize(), rotate() methods, when the object is scaled or rotated, but its transparency mask remains unchanged.