Before we go too far we should probably start working on using gettext.
I'm not particularly experienced in gettext myself and have no idea how to set it up & combine with Flatpak but we should probably work on it whilst we only have a small number of strings
It may be that it's a long time before we have anything other than
en_US but we definitely won't get translators if we don't provide the infrastructure.
I know GSoC Eisha Chen-Yen-Su has been working on this in Fractal so their blog/commits maybe of help in this