An in-depth analysis of phase transformations in a Pd–Cu–Ag alloy, crucial for applications in hydrogen membranes and electrical components, is presented. The investigation emphasizes the influence of the deformation rate and addition of Ag on the formation of the ordered CuPd phase. This study focuses on a specific alloy composition, 49.1% Cu–41.3% Pd–8.3% Ag–1.3% Ru, investigating its behavior under various conditions. Through comprehensive analysis, including the influence of the initial state, deformation variations, and chemical composition modifications, high-energy X-ray diffraction to unveil detailed phase evolution dynamics is used. Surprisingly, experimental findings deviate from the anticipated phase diagram, uncovering a previously unrecognized three-phase region with the formation of AgPd. Notably, the study reveals the pivotal role of the alloy's Ag content in the development of ordered CuPd and AgPd phases. The addition of Ru exhibits no involvement in the observed phase transformations, contributing to the understanding of the alloy's composition-dependent behavior. This research provides valuable insights into the intricate interplay of factors influencing phase transformations, offering a nuanced perspective beyond theoretical predictions. The newfound understanding of Ag's role and Ru's inertness refines material design considerations, enhancing the grasp of the alloy's thermodynamic stability under varying conditions.