Looking into the use of the raw system-ui keyword, I noticed most websites/css frameworks don't use it and instead just have the compiled list of fallbacks. This post by Joan Xie details that it has something to do with the fact that certain versions of Windows set with non-English languages don't handle the system-ui keyword correctly.

Does it make sense to give users the option to not preserve the system-ui keyword and instead just use the fallbacks? Similar to how postcss-custom-properties handles preservation of custom properties.

This way a user doesn't need to supply their own family option to fix this issue and still gets the benefits of postcss-font-family-system-ui constructing the list of fallbacks.