The “Multi Lang Support Test-1634548513383.pdf” file you shared was actually produced by using old 21.7 version of Aspose.Words for Java. Please upgrade to 21.9 version and see how it goes on your end?
You can also try installing the 'Arial Unicode MS’ font file on your machine where you are getting this problem. You may download it from following link:
In case the problem still remains, as requested earlier, please ZIP and upload your input HTML file (that you are getting this problem with) here for testing. We will then investigate the issue on our end and provide you more information.