This study conducts a comprehensive comparison of three leading LLMs—GPT-4, Claude 3, and Gemini—in two translation-related tasks: automatic post-editing and MQM error annotation, across four languages. Utilizing the pharmaceutical EMEA corpus to maintain domain specificity and minimize data contamination, the research examines the models’ performance in these two tasks. Our findings reveal the nuanced capabilities of LLMs in handling MTPE and MQM tasks, hinting at the potential of these models in streamlining and optimizing translation workflows. Future directions include fine-tuning LLMs for task-specific improvements and exploring the integration of style guides for enhanced translation quality.