We are not passing the unicode option to archy here https://github.com/isaacs/npm/blob/a362c3f1919987419ed8a37c8defa19d2e6697b0/lib/install.js#L433
What does the unicode config option do? Is it documented in npm somewhere?
Yes, it's documented here https://github.com/isaacs/npm/blob/master/doc/misc/npm-config.md
Hmm OK. Seems like an easy pull request if you want to try your hand at it. Some before/after screenshots would be especially good to see.