Weak Optical Accessibility and Externally Calibrated Halo Inference in Candidate Dark Galaxy-2

This technical note examines Candidate Dark Galaxy-2 (CDG-2) as a local diagnostic case of weak optical accessibility with layered evidential structure. The goal is not to propose a new theory of the dark sector, but to distinguish more carefully between three inferential levels that are often compressed into a single discovery narrative: conservative directly reconstructible quantities, object-level stabilization through convergent observational support, and stronger halo-level quantification obtained through externally calibrated globular-cluster-to-halo relations. Using a minimal literature-based audit, the note reconstructs the conservative globular-cluster light fraction, the stronger canonical-GCLF scenario, and the extreme halo-dominance estimates derived from published scaling relations. The main result is methodological: the existence of an extremely faint galactic system is supported by a layered observational pathway involving compact tracers and diffuse-light detection, whereas the strongest halo-level claim depends on transferred empirical closure rather than on equally direct manifestation. The note also highlights the non-negligible domain-shift risk introduced when broad empirical calibrations are transported into such an unusually faint and extreme regime. CDG-2 is therefore treated as a diagnostic case of weak manifestation, partial stabilization, and externally strengthened halo inference, rather than as a uniform evidential block.