Designing accessible user interfaces (UIs) for literacy-challenged populations in Africa is crucial to ensure equitable access to technology and services. A mixed-methods approach was employed, including surveys (N=200) and user testing sessions (n=50). Findings revealed that a simplified visual interface design reduced error rates by 15% in literacy-challenged users compared to standard designs. The comparative study demonstrated the significant impact of UI simplification on usability among low-literacy populations, particularly when using statistical models for user testing data analysis. Further research should explore scalable UI design solutions and potential applications beyond Uganda's context.