The developers (Crate Entertainment) have officially stated: Since the Quest Tracker is a single-player UI modification and doesn't spawn items or grant god mode, it is 100% legal and safe for Steam Achievements.
The is an open-source tool hosted on GitHub that allows players to track quest status outside the standard game interface. grim dawn quest tracker mod
One crucial detail that the Grim Dawn Quest Tracker Mod reveals painfully: grim dawn quest tracker mod