Name Consistency in LLM-based Machine Translation of Historical Texts

Dominic P. Fischer, Martin Volk


Abstract
Large Language Models (LLMs) excel at translating 16th-century letters from Latin and Early New High German to modern English and German. While they perform well at translating well-known historical city names (e.g., Lutetia –> Paris), their ability to handle person names (e.g., Theodor Bibliander) or lesser-known toponyms (e.g., Augusta Vindelicorum –> Augsburg) remains unclear. This study investigates LLM-based translations of person and place names across various frequency bands in a corpus of 16th-century letters. Our results show that LLMs struggle with person names, achieving accuracies around 60%, but perform better with place names, reaching accuracies around 90%. We further demonstrate that including a translation suggestion for the proper noun in the prompt substantially boosts accuracy, yielding highly reliable results.
Anthology ID:
2025.mtsummit-1.16
Volume:
Proceedings of Machine Translation Summit XX: Volume 1
Month:
June
Year:
2025
Address:
Geneva, Switzerland
Editors:
Pierrette Bouillon, Johanna Gerlach, Sabrina Girletti, Lise Volkart, Raphael Rubino, Rico Sennrich, Ana C. Farinha, Marco Gaido, Joke Daems, Dorothy Kenny, Helena Moniz, Sara Szoc
Venue:
MTSummit
SIG:
Publisher:
European Association for Machine Translation
Note:
Pages:
204–219
Language:
URL:
https://preview.aclanthology.org/mtsummit-25-ingestion/2025.mtsummit-1.16/
DOI:
Bibkey:
Cite (ACL):
Dominic P. Fischer and Martin Volk. 2025. Name Consistency in LLM-based Machine Translation of Historical Texts. In Proceedings of Machine Translation Summit XX: Volume 1, pages 204–219, Geneva, Switzerland. European Association for Machine Translation.
Cite (Informal):
Name Consistency in LLM-based Machine Translation of Historical Texts (Fischer & Volk, MTSummit 2025)
Copy Citation:
PDF:
https://preview.aclanthology.org/mtsummit-25-ingestion/2025.mtsummit-1.16.pdf