Is For Honor cross platform / cross region?
Faction wars (metagame) are cross platform, but the actual gameplay isn't.
You can play cross region, but as you have noticed it first searches in your region (EU for Europe, NA if you're in North America, etc.) before searching in all regions. Normally a game does this because it's easier to find and maintain a connection within the same region.
I'm fairly certain you could make it so it always searches across all regions, but someone will have to confirm that.