The title made only by katakana character, would be mojibake.

[mimosafa]

# site.yml
lang: ja
title: アイウエオカキクケコ

If defined above, the title will be '繧｢繧､繧ｦ繧ｨ繧ｪ繧ｫ繧ｭ繧ｯ繧ｱ繧ｳ'.

# site.yml
lang: ja
title: アイウエオ下記九家粉

This is no problem.

OS: Windows 10
VirtualBox: 5.1.8
Vagrant: 1.8.6
VCCW: 3.0.0-beta5

(But, I have no clue whether the problem caused by vccw.)

[miya0001]

Is your site.yml UTF-8?

[mimosafa]

Yes...

$ file --mime site.yml
site.yml: text/plain; charset=utf-8