It could also just be metaphorical. A chisel is a shaping tool for stone, and the drawing comes right when Shallan is learning to con, which she associates heavily with her own identity, specifically in "choosing" who she needs/wants to be. Neither of the drawings has to be far-seeing.
Also Shallash used a hammer in the interlude, though I wouldn't preclude chisels just from that.
Also did anyone else notice that several times during the first two novels when characters are looking at depictions of the heralds one of them is missing/destroyed? I seem to recall one in Gavilar's castle I thought referenced Jasnah moving a statue to attempt to protect from her spren, but then the painting in the Prime's rooms in the Lift interlude made me think otherwise. Is there any more evidence that Shallash might be destroying specifically art depicting one or more of the heralds?