YAG Laser’s output infrared light. Arc Welding puts out UV. These are opposite ends of the visible light spectrum. Welding curtain doesn’t protect against Infrared, which is specifically highly damaging to eyes.
The simplest solution is moveable solid walls, preferably with interlocks. Improved visibility of jobs can be achieved by the installation of a simple camera/monitor circuit, or for a failproof method laser protective glass panel into the walls (can be rather expensive, but can also be retrofitted).