While bsdinstall(8) allows users to choose keyboard layout, and puts the correct "keymap" line to /etc/rc.conf, it doesn't allow for changing the font. From the user point of view, this makes national characters simply not work - pressing "alt-whatever" results in garbage on the screen. This does not affect 11-CURRENT, as the vt(4) uses UTF-8 by default.
It appears this is the case for all releases from 9.0 on, after the switch to bsdinstall happened. https://www.freebsd.org/releases/9.0R/announce.html