No verified public rebuildable Far Cry 5/Dunia engine or source reconstruction was found in the sources reviewed. There are public tools for archive extraction, data/script conversion, and partial static-mesh export. Those are file-format tools, not a recovered game engine or complete asset pipeline.
Ubisoft describes Far Cry Arcade as Far Cry 5's map editor mode, with maps connected to the game and its shared progression. The official editor guide documents more than 10,000 objects from six Ubisoft game families, plus terrain, weather, AI, objectives, and loadouts. This is a capable FC5 map-authoring environment, not a general-purpose engine export path.
Steve64b's community Editor Mod extends that same PC editor. The author describes additional editor assets and features, while noting that vanilla compatibility depends on avoiding mod-only objects. Separate Unreal examples cite FC5 design inspiration and disclose independent engines or asset packs; they do not claim importing raw FC5 files.
No reviewed primary source verifies a public Far Cry 5 engine/source reconstruction or a standalone game built from extracted FC5 assets. This is bounded to the public sources reviewed; it does not rule out private or unindexed work.