Unfortunately, “Auto Mask” generally does not work in a reasonable way at all. 
Also see Shortcut to observe the actual auto-mask?
(and the links provided in that thread).
Being able to automatically recognize a clicked “object” is even harder to implement. While it might be nice to have such a feature sometimes in the future, IMHO it’s far more urgent to finally fix “Auto Mask” at all.
Meanwhile it’s four years (!) since the fix has been promised to come “soon”.