Worked on the mbta/api repository to deliver internationalization enhancements for the cause_detail and effect_detail fields, enabling the API to support both translated objects and strings while maintaining backward compatibility. Applied Elixir and backend development skills to update parsing logic and expand test coverage, ensuring that new multilingual formats are robustly handled. Focused on reducing localization-related maintenance risk and supporting future multilingual deployments by updating tests to exercise both legacy and new formats. This work improved localization support for downstream integrations and positioned the API for broader global usage, demonstrating a methodical approach to API development and internationalization challenges.