Abstract: Proton therapy is a precise cancer treatment that requires meticulous planning to deliver the prescribed dose to the target volume, while sparing healthy tissues. Compton cameras have emerged as a promising technology for in-vivo proton range verification through prompt-gamma detection, given their compactness and compatibility with the treatment gantry. This study evaluates the performance of the MACACOp Compton camera prototype, developed by the IRIS group at IFIC-Valencia, under progressively challenging conditions across several proton therapy facilities. The MACACOp camera, featuring monolithic LaBr3:Ce crystals and SiPM arrays, was tested at the Centro Nacional de Aceleradores, Cyclotron Center Bronowice, and Centro de Protonterapia Quir & oacute;nsalud. Under controlled conditions, the prototype was able to detect changes in photon emission distribution with high precision, resolving 1 mm displacements of a graphite target irradiated with a 8 nA proton beam, with the camera at 200 mm from the target. Additionally, the camera's enhanced timing resolution of 1.5 ns facilitates background rejection, an essential feature for proton therapy monitoring. Building on these results, the FALCON prototype was evaluated, demonstrating improved efficiency and the ability to reconstruct spots even under more challenging accelerator conditions. These findings underscore the potential of Compton cameras for real-time proton range verification, advancing their integration into clinical proton therapy systems.