Pango was last updated 3 years ago to 1.32.5. I was under a wrong impression that we would stop using it and hanve't paid attention to it. 

Recently, I found that even Pango 1.38 (1.5 years old) has an issue with old Hangul (+ the latest harfbuzz). Pango 1.42 (the latest release) does not. 

We also have to look at the cairo.