← Project list

Fasoo/Sparrow Internship · Applied ML

WatchTower

A public reconstruction of an internship project that evaluated Korean-to-English product copy with multiple quality signals and post-edited only translations that required review.

Role
Fasoo / Sparrow internship · Evaluation pipeline design and public reconstruction
Technologies
Python · LaBSE · COMET · LLM Evaluation · NLP
Cover page of a presentation on an AI agent for translation-quality validation
Presentation cover. Open the full 16-page PDF for the complete report.
WatchTower pipeline connecting LaBSE, COMET, and GEMBA evaluations to a Q-Score and selective post-editing
tkim602/WatchTower · README.md
Evaluation throughput
About 2,500 sentences/hour

Maximum observed during the internship evaluation

Quality-grade improvement
68%

Share of selected translations whose grade improved after post-editing

01

Context

Translation errors in multilingual product copy are uncommon, but their impact can be significant. A changed term, damaged placeholder, or altered technical identifier can affect both product behavior and user understanding. Reviewing every sentence at the same depth spends most of the effort on translations that are already acceptable.

The goal was not to remove final human review. It was to surface the translations most likely to contain errors. The pipeline needed to check meaning preservation, language quality, and format stability without a reference translation, then evaluate post-edited text with the same criteria.

02

Engineering

LaBSE measures semantic similarity between Korean source text and English translation, while COMET provides a learned quality signal. A GEMBA-style LLM evaluation covers mistranslations that are difficult to express as rules. Deterministic checks inspect terminology, placeholders, technical identifiers, and unusual length changes.

The signals are normalized into a Q-Score, and only low-scoring translations are post-edited. Revised sentences pass through the same evaluation again, while final approval remains with a human reviewer. The public repository is a reduced reconstruction of the decision flow, not a copy of company code.

My contribution

  • Designed the end-to-end flow for reference-free translation evaluation and selective post-editing.
  • Normalized semantic, learned-quality, and format-check signals so they could be compared in one score system.
  • Created reproducible public examples and documentation without exposing company data or internal implementation details.

Key technical decisions

Use a different check for each error class

Semantic similarity alone can miss damaged placeholders, while deterministic rules cannot reliably identify fluent mistranslations. Each evaluator retains the error class it is best suited to detect instead of delegating every decision to one model.

Post-edit only low-quality translations

Regenerating acceptable translations increases cost and regression risk. Only selected sentences are revised and evaluated again. The Q-Score prioritizes human review; it does not make the final approval decision.

03

Validation

Throughput and quality grades before and after post-editing were measured in the internship environment. The figures above describe the selected post-editing set, not all translations, and are not synthetic benchmark results from the public reconstruction.

Verified results

  • Changed a uniform review queue into a risk-prioritized list of translations.
  • Repeated the same evaluation after post-editing to verify that a revision improved the measured quality signals.

Failures and changes

  • A single threshold missed either semantic errors or formatting failures. The final pipeline preserved each signal and compared them through a normalized Q-Score.

Next steps

  • The public repository excludes sensitive company code and data. Public multilingual datasets could support a new calibration of domain-specific thresholds and error-class priorities.
  • The 68% figure applies only to translations selected for post-editing. A larger control group and longer evaluation would be needed to measure total review time and recurrence rates.