For such tasks GIMP (including Gmic) is simply the better tool. I’m happy, that there is a retouch tool in darktable. It’s perfect to remove smaller annoyances like sensor spots. But for proper retouch work, GIMP is so much better…
I’m sure you will find it hard to find traces of the cables, even when you zoom in to 100%:
The way how I did it is already described here: Ugh... Powerlines! - #4 by Popanz