This may or may not be useful, and I am certainly not part of CS... however, I have been around the industry for some time and have worked with many various companies.

If ANYTHING inside the cfg file is different, or file structure or otherwise, it WILL give this error. For example, I have ASA which adds an additional weather panel to the .cfg. I get this error all the time when flying with others. It however creates no issues.

I suspect regardless of the error, this plane will not work in multiplayer due to the custom coding.