The accents are badly encoded.
examples : é -> <C3><A9>
ô -> <C3><B4>
Could you provide more info? 🤔 When this happens?

Same problem here with german umlauts(äöü). I'm using hyper after a clean Install without plugins and with zsh on macOS 10.12.2 and QWERTZ(German) keyboard layout.
seems related to locale
chabou@DeLorean: ~
$ locale
LANG="fr.UTF-8"
LC_COLLATE="C"
LC_CTYPE="C"
LC_MESSAGES="C"
LC_MONETARY="C"
LC_NUMERIC="C"
LC_TIME="C"
LC_ALL=
chabou@DeLorean: ~
$ ls /tmp/dévelop
'/tmp/d'$'\303\251''velop'
chabou@DeLorean: ~
$ export LANG="fr_FR.UTF-8"
chabou@DeLorean: ~
$ ls /tmp/dévelop
/tmp/dévelop
But there is a strange thing (in bahs and zsh):
chabou@DeLorean: ~
$ ls -l /tmp/dévelop
-rw-r--r-- 1 chabou wheel 0 jan 7 16:55 /tmp/dévelop
chabou@DeLorean: ~
$ ls -l /tmp/
total 0
-rw-r--r-- 1 chabou wheel 0 jan 7 16:55 develop
Does not happen in Terminal.app
Is there any update? Still cannot write or display German Umlaute (ä,ö,ü,ß).
Is there any update? Same for me.
@schneyra We're tracking this work over here (with workaround explained): #607
There is an outdate PR here: https://github.com/zeit/hyper/pull/605
Most helpful comment
seems related to locale
But there is a strange thing (in bahs and zsh):
Does not happen in Terminal.app