The advent of two-dimensional (2D) magnets has unlocked new opportunities in spintronics and quantum science; however, a lack of effective characterization techniques has left many aspects of spin transport and twist-induced phenomena largely unexplored. In CrSBr, the strong spin-exciton coupling offers unique potential for precise optical measurements of spin degrees of freedom. Using temporally and spatially resolved optical techniques, our work demonstrates that magnon transport in CrSBr is mediated by long-range dipole–dipole interactions—a fundamental feature of electrodynamics likely to govern spin propagation at long wavelengths in the entire class of van der Waals magnets. Furthermore, we employ magnons to probe twisted CrSBr interfaces, where quantitative information about interfacial exchange interactions and hopping can be obtained. Together, these studies establish magnons as a powerful tool for probing interactions and uncovering new phenomena in 2D magnets and other quantum materials.