Show Me All Writing Errors: A Two-Phased Grammatical Error Corrector for Romanian

Nowadays, grammatical error correction (GEC) has a significant role in writing since even native speakers often face challenges with proficient writing. This research is focused on developing a methodology to correct grammatical errors in the Romanian language, a less-resourced language for which there are currently no up-to-date GEC solutions. Our main contributions include an open-source synthetic dataset of 345,403 Romanian sentences, a manually curated dataset of 3054 social media comments, a two-phased GEC approach, and a comparison with several Romanian models, including RoMistral and RoLama3, but also LanguageTool, GPT-4o mini, and GPT-4o. We consider a synthetic dataset to finetune our models, while we rely on two real-life datasets with genuine human mistakes (i.e., CNA and RoComments) to evaluate performance. Building an artificial dataset was necessary because of the scarcity of real-life mistake datasets, whereas introducing RoComments, a new genuine dataset, is argued by the necessity to cover errors amongst native speakers encountered in social media comments. We also introduce a two-phased approach, where we first identify the location of erroneous tokens in the sentence; next, the erroneous tokens are replaced by an encoder–decoder model. Our approach achieved an F0.5 of 0.57 on CNA and 0.64 on RoComments, surpassing by a considerable margin LanguageTool as well as an end-to-end version based on Flan-T5 and mT0 in most setups. While our two-phased method did not outperform GPT-4o, arguably by its smaller size and language exposure, it obtained on-par results with GPT-4o mini and achieved higher performance than all Romanian LLMs.