Garion contributed backend improvements to the pinterest/mojito repository, focusing on enhancing API reliability and data safety. He addressed a type mismatch in the BranchStatistics API by refining the join logic between BranchStatistic and Branch entities, ensuring accurate branchId filtering using JPA/Hibernate and Java. Additionally, he improved the WordCountService by updating getEnglishWordCount to safely handle null or empty input, preventing potential NullPointerExceptions. Garion reinforced these changes with targeted unit tests, increasing test coverage and documenting intended behaviors. His work demonstrated a methodical approach to bug resolution, emphasizing robust data correctness and maintainability within the existing Java backend infrastructure.