what does it mean to 1-turn a country? I keep seeing that term but I do not understand. My guess is you liberate a country in one turn, but wont the quest end after you defeat a fiend? Or is it by winning the first appearance
Did you manage to find an interface patch, or just soldiering on regardless?
1 turning a country means defeating both 魔人 in the same phase. Sometimes this means you have to win in the first encounter, sometimes it just means you have to win before the final encounter. You can usually tell by looking at how the path forks in the map if you'll get another chance.
Regardless, you will almost never get to rest between the fights and both battles tend to be the hardest variant of each so 1 turning (or double suppression as is the term the game uses) is probably not something you can pull off without some NG+ bonuses, or towards the mid/end game of a good NG run.
You also on net get much fewer cards and probably also less xp for double suppressing relative to normal clears, so you get weaker relative to the difficulty curve when you do it.