It's translateable, just not in hexoshi.pot. You can just add the string to the .po file you're making if you want; it will translate it since it makes gettext calls on timeline dialog strings.

hexoshi.pot is auto-generated right now, so I don't want to make manual edits to it. The plan is to switch it to a manually updated file when the game is closer to completion.

I've changed the name of this bug to more accurately reflect what it is, and set the status to "Postponed". Feel free to add t his entry in your .po files; .pot generation doesn't erase those, so it's no problem.