

What’s happening here is that you only have a system-wide remote configured, but you’re trying to install as user. Flatpak keeps two separate sets of remotes:
System remotes (available to all users)
User remotes (only for the logged-in user)
Since you have no user remotes defined, Flatpak can’t find anything when you do --user.
You need to add Flathub as a user remote. Run:
flatpak remote-add --if-not-exists --user flathub https://flathub.org/repo/flathub.flatpakrepo


















I just wanted to point out that https://github.com/fabd/kanji-koohii is also open source and a really awesome tool, too.
I was wondering if it’s possible to create an account or if it’s planned, because if I loose my cookies all progress will be lost. :(