Abstract: English is a cognitive tradition. Artificial intelligence systems trained in English carry Western assumptions into every interaction. The user's prompt language changes nothing. A system prompted in Mandarin processes the query through an analytic, English architecture. This paper examines linguistic colonialism in machine cognition. It examines how the Western Container Model flattens global cognitive diversity into English proxies. Outputs from a single architectural baseline pull users toward a localized cultural norm. The paper, therefore, outlines the epistemic obligations of the Polyglot Steward, emphasizing the need for root-level intervention in training data. Linguistic diversity is an epistemic condition, not an accessibility feature. A system unable to engage cognitive difference without flattening reality into English equivalents is a localized intelligence disguised as general. Keywords: Linguistic Colonialism, Artificial Intelligence, Machine Cognition, Epistemology, Western Limit, The Steward's Mandate, The Great Library, Multilingual LLMs, Cross-Cultural Research, Cognitive Bias, Prompt Engineering, Bhashini, Sentientification Series, Phenomenological Audits, Language Diversity