George, we've confirmed the issue on our end and filed a bug. It does look like we're having issues with multiline "auto" font size. Please watch for updates and thank you for reporting the issue.
We looked at the string. The encoding of the string appears to be unusual (not sure if it is or is not compliant with the PDF specification). However, in general, we'd like to be able to show PDF content that the desktop Adobe Reader can, so we'd consider this a bug as well. I've filed that bug. Is it possible to share what you used to generate this PDF?