One has to be careful with the ‘/’ token.
KiCad has decided to use it to denote hierarchical node labels. So if you place a local ‘out’ node label, you will get a ‘/out’ as ngspice input.
ngspice has several commands (I guess including wrdata) that allow not only to place vectors (simulation results) for specific nodes, e.g. like V(out), but also equations of results (e.g. like V(out)/2) as their arguments. You even might give only out/2 as an argument (instead of V(out)/2).
Now what to do with V(/out)? /out as a node name is o.k. for ngspice, as a command argument it may be not. So we have to use V("/out") to survive the equation parser.
This is unfortunate, has been discussed with the KiCad devs, but for the moment there is not a really good solution at hand.