Evaluation of Two Leading Polish Language Models in a Real-world RAG Scenario

Szymon Bartanowicz, Krzysztof Jassem


Abstract
This paper presents a comparative evaluation of two leading Polish instruction-tuned language models, Bielik-11B-v2.3-Instruct and PLLuM-12B-nc-chat, within a real-world Retrieval-Augmented Generation (RAG) system designed for the technical documentation of a low-code platform. The study aims to identify the optimal configuration of retrieval and generation components for Polish-language applications. The evaluation was conducted in two stages. First, several embedding models and retrieval methods were tested using standard information retrieval metrics, including NDCG. The OrlikB/KartonBERT-USE-base-v1 model combined with vector-based retrieval achieved the highest performance and was adopted for the second stage. In the generation phase, both models were evaluated using quantitative scoring and pairwise A/B testing with multiple evaluators to ensure robustness. Results show that Bielik-11B-v2.3-Instruct consistently outperformed PLLuM-12B-nc-chat in producing accurate and contextually relevant answers. The study highlights the importance of constructing a reliable golden set, employing a two-phase evaluation pipeline, and selecting appropriate metrics to ensure objective and reproducible assessment of RAG systems in real-world Polish-language contexts.
Anthology ID:
2026.lrec-1.211
Volume:
Proceedings of the Fifteenth Language Resources and Evaluation Conference
Month:
May
Year:
2026
Address:
Palma de Mallorca, Spain
Editors:
Stelios Piperidis, Núria Bel, Henk van den Heuvel, Nancy Ide, Simon Krek, Antonio Toral
Venue:
LREC
SIG:
Publisher:
ELRA Language Resource Association
Note:
Pages:
2698–2704
Language:
External URL:
https://lrec.elra.info/lrec2026-main-211
DOI:
10.63317/36igcwtic7tn
Bibkey:
Cite (ACL):
Szymon Bartanowicz and Krzysztof Jassem. 2026. Evaluation of Two Leading Polish Language Models in a Real-world RAG Scenario. In Proceedings of the Fifteenth Language Resources and Evaluation Conference, pages 2698–2704, Palma de Mallorca, Spain. ELRA Language Resource Association.
Cite (Informal):
Evaluation of Two Leading Polish Language Models in a Real-world RAG Scenario (Bartanowicz & Jassem, LREC 2026)
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