Scott Duncan writes a short book entitled "Understanding Agile Values and Principles: An Agile Manifest Exam," published by InfoQ and freely available in PDF format, which delves into the manifesto for agile software development and its values and principles. The following is a summary of his thinking.
Duncan relates "customer collaboration on contract negotiation" with "individuals and interactions about processes and tools". While the value of "individuals and interactions" refers to the internal functioning of the development organization and the development team, the value of "collaboration with the client" refers to how the development organization or development team interacts with External stakeholders The collaboration here refers to how the development team and external stakeholders find methods to understand user requirements and needs, verify and validate the functionality delivered and exchange comments on how to improve interactions.
The "response to change after following a plan" focuses on the waste associated with long-term planning. Recognize that software development is complex and unpredictable. Instead of estimating what is believed to be the full scope of the work in advance and delivering it once, this value is about the iterative nature of regularly reviewing the work and adapting to the changing environment in which the software is implemented and used and Changes in understanding user requirements. It is related in some way to the "work software on complete documentation", and together these two values lead to iterative and incremental development models.
I see some relationship between the values of "collaboration with the customer" and "respond to change", as you point out. Sometimes, the lines between how the team works with stakeholders and what the team builds for stakeholders can blur when defining contracts, plans and requirements. However, the intention seems clear.
My suggestion would be to not take any of the four values in isolation. There are definitely interactions and relationships between the four.