Claude Haiku 4.5 vs Codestral 2508 for Translation

What Translation demands: accurate cross-language equivalence, preservation of tone/idiom (localization), strict faithfulness to source content, and the ability to handle long documents or structured outputs. In our testing, the primary measure for this task is the Translation task score (derived from multilingual and faithfulness tests). Claude Haiku 4.5 leads on that primary measure (5.0 vs 4.5). Supporting evidence from our internal probes: Claude Haiku 4.5 scores 5 in multilingual and 5 in faithfulness, plus a persona_consistency 5 — all useful for tone-preserving localization. Codestral 2508 scores 4 in multilingual and 5 in faithfulness, but it scores 5 in structured_output, which matters when translations must conform to a JSON schema or downstream parser. Both models tie at 5 for long_context and 5 for tool_calling, so very long documents and tool-invoked workflows are supported by both. Cost and throughput also matter: Claude Haiku 4.5 has input/output costs 1 / 5 per mTok, while Codestral 2508 is cheaper at 0.3 / 0.9 per mTok, which affects large-volume translation budgets.

Where Claude Haiku 4.5 shines: 1) Marketing website localization that must keep brand voice and idiom—Claude scores 5 multilingual and 5 persona_consistency, so tone and cultural nuance are better preserved. 2) High-stakes PR or legal localization where preserving subtle meaning is critical—Claude's faithfulness 5 and multilingual 5 minimize meaning drift. Where Codestral 2508 shines: 1) High-volume batch translation pipelines requiring strict JSON outputs—Codestral's structured_output 5 and lower output cost (0.9 per mTok) reduce parsing errors and cost. 2) Low-latency, code-adjacent translation tasks or FIM-style replacements where throughput and cost matter—Codestral's description and pricing make it practical. Near-tie scenario: Long technical manuals—both models score 5 on long_context and 5 on faithfulness, so either can handle long documents, but choose Claude if tone/naturalness matters or Codestral if you must enforce rigid output schemas and minimize cost.

For Translation, choose Claude Haiku 4.5 if you need the highest-quality multilingual output, tone preservation, and localization (scores: Translation 5.0; multilingual 5; persona_consistency 5). Choose Codestral 2508 if you need lower-cost, high-throughput translation with strict structured outputs (Translation 4.5; structured_output 5; input/output costs 0.3 / 0.9 per mTok).