As is often said, quantity is a quality all it's own. The empire is starting to run low on reasonably draftable people while they, geographically speaking, are lining up to have a mirror match of Germany in WW2. The moment the russians declare war it will likely bring in the brits, since they are already sending volunteers and supplies to people, and the US since the girl that got triple blessed is there and god wants to fuck around. Without a nutjob like hitler in charge, all it takes is for one front to collapse and the empire offers a surrender while they can still get terms without total occupation.
As for the info blackout, only a few people know of her appearance or actual name outside the empire. So far the only enemy to have seen her in decent conditions, so not in a storm at sea right after some explosions, and lived was the mage commander of the french, and that's assuming he lives to the end of the war. And no one actually knows any of her titles or name outside of devil of the rhine so far. There might be more in coming chapters but the number is probably going to stay under double digits, so it'd be unlikely for foreign nations to have detailed reports. All the info they have is likely what they got from the empire after it surrendered and had it's military intel and whatnot either looted or offered up in the surrender which was likely censored by the people in the empire first. There are quite a few possible reasons for those in the empire covering it up though. Tanya would likely be considered a war criminal, or at least treated like one judicially, after the war from burning down the city of arren alone, let alone what she ends up doing to communists. She could also just call in a bunch of favors since she has connections with most of the upper brass that knows more than her name and unit number, or they could have just done it to save their own asses for being associated with her. Hard to say in that regard.
