Yes, one can copy the contents of the terminal to the clipboard
It's confusing in this context to keep calling it "terminal" as that means a completely different part of Geany's UI (the "Terminal" tab, containing an actual terminal emulator). This is why I changed the title/description.
we must fight this decline by constantly improving our favorite tools so that we do not decline too.
I'm pretty sure a well written patch that goes through the compiler tab's tree view and finds things that look like filenames and hyperlinks them to open in the editor would be accepted, especially if it was optional.