Is it possible to create a script so that when highlighting a text it is also copied? (to the clipboard) I would appreciate the answer, it would be very useful to know if it can be done or not. Thank you.
As far as I know, this is not possible with just a script. A script does not have access to notifications from the highlight tool, so would not know that you've just highlighted text in your document. It can be done with an custom Acrobat plug-in, but that's when it gets expensive.
A script also can't copy anything, so the answer is definitely no.