Claude Haiku 4.5 vs Codestral 2508 for Multilingual

Multilingual demands equivalent quality in non‑English languages: accurate grammar and idiom use, consistent tone and persona across translations, faithful adherence to source content, and robust handling of long multilingual contexts (e.g., documents, conversation history). In our testing the primary signal is the Multilingual task score: Claude Haiku 4.5 = 5, Codestral 2508 = 4. Supporting proxies explain why: Claude pairs that 5 with faithfulness 5, persona consistency 5 and long context 5 — strengths that reduce mistranslation, maintain voice, and preserve context over long multilingual inputs. Codestral scores 5 on structured output and 5 on long context and tool calling, which helps strict format outputs and function sequencing, but its lower persona consistency (3) and creative problem solving (2) make it likelier to miss subtle tone or idiomatic choices in non‑English content.

Where Claude Haiku 4.5 shines (based on scores):

• Customer support localization: Claude’s Multilingual 5 and persona consistency 5 keep brand voice consistent across languages for long ticket threads (long context 5, faithfulness 5).
• Literary or marketing copy adaptation: high persona consistency and faithfulness reduce unnatural literal translations and preserve style.
• Multi‑document analysis in non‑English: long context 5 preserves references across long inputs. Where Codestral 2508 shines (based on scores):
• Structured multilingual outputs (APIs, JSON, CSV): structured output 5 gives stricter schema compliance than Claude’s 4.
• Low‑cost, high‑volume multilingual preprocessing: lower output cost ($0.90 / mTok vs Claude’s $5 / mTok) makes Codestral better for bulk tasks where a 1‑point multilingual delta is acceptable.
• Tooled workflows requiring precise function calls in multiple languages: tool calling 5 matches Claude here, but Codestral’s lower persona consistency (3) means human review for tone-sensitive text is advisable.

For Multilingual, choose Claude Haiku 4.5 if you need the highest non‑English quality, consistent tone, and long‑document fidelity (scores: Multilingual 5, faithfulness 5, persona consistency 5). Choose Codestral 2508 if you need lower cost and top structured-output or tool-calling performance with good multilingual adequacy (Multilingual 4, structured output 5) and can accept occasional tone/nuance gaps.