This contribution investigates the notion of reliability within HBIM processes applied to historical built heritage, emphasizing that model quality arises not merely from geometric accuracy, but from the epistemic transparency of the knowledge framework underpinning its construction. By integrating documentary research, instrumental survey data, and interpretative modeling practices, the study outlines a structured methodology for encoding and conveying both uncertainty and informational consistency. The proposed system promotes a shift from the pursuit of geometrically “perfect” representations toward models characterized by traceability, semantic rigor, and critical accountability. An HBIM model may be deemed truly informative only when it makes explicit its limitations, assumptions, and the provenance of its data.