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Quantum Darwinism (QD) and Spectrum Broadcast Structure (SBS) formalize a mechanism by which many observers can learn the same classical pointer value of a system by measuring different fragments of its environment. Most QD analyses treat the observer as idealized: unlimited access, perfect calibration, and no temporal constraints. This paper introduces an explicit observer quality parameterization and propagates it through redundancy and objectivity statements in a way that remains stable under an explicit ε-SBS trace-distance error model. Our main technical contributions are: (i) a decoder-level, tight (Chernoff-optimal) sample-complexity characterization for the number of environmental fragments needed to infer a pointer value under a calibrated observer model, (ii) a data-processing theorem showing that calibration noise (modeled as a CPTP channel) degrades the quantum Chernoff exponent, and (iii) an ε-robustness theorem upgrading ideal-SBS sample-complexity bounds to approximate-SBS states with additive error control. We ground the formalism in a fully worked open-system example: a central-spin pure-dephasing model whose conditional fragment states can be computed analytically, yielding explicit formulas for the observer parameters (R_O, C_O, τ_O) as functions of couplings, readout noise, and acquisition time. We also highlight a sharp performance gap between collective (coherent) decoding and product-measurement decoding for pure-state records, directly linking quantum memory horizon to redundancy. Finally, to connect this physics formalism to the DLN observer-quality framework, we introduce a three-state stage index q_O ∈ {q_D, q_L, q_N} mapping Dot/Linear/Network stages to memoryless, product, and collective decoding classes. We then prove three dynamical results about observer topology over time: (A) a dynamical redundancy theorem showing that the long-run effective Chernoff exponent depends on the observer's revision topology R_O, with full-cycle revision achieving the adaptive optimum while expand-only revision collapses permanently to the linear baseline; (B) an "inverted sophistication" theorem showing that an unmonitored collective decoder can be strictly worse than optimal product decoding below a critical coherence fraction; and (C) a pointer-accessibility proposition formalizing how the DLN stage determines which pointer distinctions are resolvable from a fixed fragment budget, providing an operational basis for observer-designed control of accessible quantum outcomes.