Ensuring confidentiality during multi-model consistency checking is a critical challenge in collaborative systems engineering. However, it is not yet clear how to assess and compare current and future solutions for multi-model consistency checking with regarding to confidentiality. Therefore, this paper introduces a formalized system model for confidentiality-preserving consistency checking. A formalization of the confidentiality preservation capability of such a system model is proposed to assess whether a given consistency checking system prevents unauthorized information leakage under specific assumptions. Based on these definitions and formalizations, we present an assessment method where an abstract system model is derived from either an implemented or conceptualized consistency checking system, and our confidentiality formalization is applied to assess the system’s guarantees for model data confidentiality. Our approach provides system and software engineers with a structured method to assess the confidentiality preservation capability regarding model data in their multi-model consistency checking systems, helping them to identify potential weaknesses and guiding improvements to enhance confidentiality where needed. To demonstrate the applicability of our framework, we apply it to an existing prototype of a partly confidentiality-preserving consistency checking system, as well as two improved versions, assessing their confidentiality preservation strengths and areas for improvement.