thylinao at ChildSafeAds 2026: A Six-Member Ensemble and What Each Level of Data Access Provided

Maksim Silchenko


Abstract
This paper describes the thylinao system for the ChildSafeAds shared task on monitoring sponsored segments in child-facing YouTube videos. The system is a six-member ensemble: two fine-tuned encoders, a zero-shot prompted Qwen3-32B, a LoRA-tuned Qwen3-14B used for ST2 only, a TF-IDF baseline, and a level-2 stacker for the compliance sub-task, blended at equal weight behind a decision layer whose every parameter is fitted on channel-grouped out-of-fold predictions. The system scores mean macro-F1 0.6537 on the evaluation split; inference over the 503 test instances is dominated by one measured 14-minute GPU pass of the 32B member. The zero-shot member is the most valuable and nearly the cheapest, while removing the fine-tuned DeBERTa changes nothing measurable. An ablation over the task’s four data access levels, run on the zero-shot member, finds the channel name adds nothing and the product-page crawl helps product identification but not, measurably, compliance. Validating these changes also surfaced properties of the evaluation, reported as feedback: the metric’s divisor dominates score variance and is recoverable in closed form from a published baseline row, and the benchmark is channel-disjoint but substantially advertiser-overlapping. The final submitted entry additionally contained three labels set by hand, which the task Terms prohibit; this was disclosed to the organisers and is documented in Section 7. The system-only score is reported throughout and no rank is claimed.
Anthology ID:
2026.nllp-1.1
Volume:
Proceedings of the Natural Legal Language Processing Workshop 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Nikolaos Aletras, Ilias Chalkidis, Leslie Barrett, Cătălina Goanță, Daniel Preoțiuc-Pietro, Gerasimos Spanakis, Shanshan Xu
Venues:
NLLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1–11
Language:
URL:
https://aclanthology.org/2026.nllp-1.1/
DOI:
Bibkey:
Cite (ACL):
Maksim Silchenko. 2026. thylinao at ChildSafeAds 2026: A Six-Member Ensemble and What Each Level of Data Access Provided. In Proceedings of the Natural Legal Language Processing Workshop 2026, pages 1–11, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
thylinao at ChildSafeAds 2026: A Six-Member Ensemble and What Each Level of Data Access Provided (Silchenko, NLLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.nllp-1.1.pdf