[The Descent Spoilers] Sacrificial Gates of Segrummar

I'm not sure. Referring to a Creator could be something that a construct like a golem might do. We thought golem making started with Caradin but they were present in the ancient thaig in DA2 so the knowledge clearly pre-dates him. A dwarf has to be sacrificed to create a golem and the dangers associated with fulfilling the commands are the reason the second writer cannot do it for themselves.

In Trespasser it is hinted that there was a time when Mythal was able to give dwarves the ability to dream, which would suggest enter the Fade, so it could be the writer was from that time? Sandal is a dwarf with magical powers who is able to dream, so he could be the last survivor of this unique group of dwarves.

It is difficult to know exactly when the words were written and to what they refer. They speak of a Sigil that has malevolent overtones and the writer suggests that the entire Deep Roads were fashioned in the shape of this sigil. Then the first writer did something to break up the lines of the sigil, which presumably broke whatever power it had. However, without being able see the remains of the sigil it is impossible to know exactly what its implications might have been.