There's a similar-but-different tool developed by SBB CFF FFS[1], it's even mentioned in the documentation of OSRD[2]. Both tools operate at different scope, if we're to believe the documentation (OSRD is micro, Netzgrafik is macro).
OP wanted something developed by the Swiss railways company though (but SISCOG seems to be used by the Dannish, Finnish, Norwegian, Canadian and Catalonian railways).
[1]: https://github.com/SchweizerischeBundesbahnen/netzgrafik-edi...
[2]: https://osrd.fr/en/docs/explanation/netzgrafik-editor/