<p>The rotation-translation coupling mechanism, critical for artificial microswimmer propulsion in biomedical and microfluidic applications, governs the directional motion near fluid-fluid interfaces. This study systematically investigates how gap size, viscosity ratio, and shear-thinning rheology modulate the translational dynamics of a sphere rotating near such interfaces. In Newtonian fluids, two distinct motion regimes emerge: sliding-dominated propulsion at low viscosity ratios and rolling-dominated motion at high viscosity ratios. The transition between these modes is controlled by tuning the viscosity ratio, with the peak transition speed observed at minimal gap sizes and decaying monotonically as the gap widens. Beyond viscosity and geometric effects, shear-thinning rheology introduces an additional mechanism for dynamic mode switching. In weakly shear-thinning fluids, four transition modes are identified: impaired rolling (IR), transition (TR), enhanced sliding (ES), and impaired sliding (IS). In contrast to IR, TR, and ES, where viscous shear forces predominantly govern the dynamics, IS is characterized by the dominance of pressure forces. Increasing shear-thinning intensity shifts dominance from the IR to TR modes, while narrowing and expanding the operational ranges of the ES and IS modes, respectively. These results establish quantitative guidelines for optimizing microroller propulsion near fluid interfaces and highlight the potential of shear-thinning rheology as a tunable parameter for advanced maneuverability in micromachines. The findings provide a framework for designing adaptive control strategies in complex fluid environments, advancing the development of next-generation microswimmers with reconfigurable locomotion capabilities. We elucidate the underlying physical mechanism and discuss its implications on the design of micromachines near fluid-fluid interfaces in complex fluids.</p>