https://bugzilla.redhat.com/show_bug.cgi?id=1004732
--- Comment #13 from Nicolas Mailhot nicolas.mailhot@laposte.net --- (In reply to Mike FABIAN from comment #4)
The screen shot attached to comment#3 shows a list of fonts used by anaconda. “Cantarell” does not support Vietnamese, “DejaVu Sans” does support Vietnamese (as shown by fc-list in comment#3).
That makes me guess what we see is a mix of “Cantarell” and “DejaVu Sans”, “Cantarell” is used as long as it has the the glyphs, for the glyphs missing in “Cantarell”, “DejaVu Sans” is used as a fallback.
Same problem as with urdu, for font substitution will only work properly in anaconda if anaconda tags its text runs with the locale they're intended for
fonts-bugs@lists.fedoraproject.org