Hmmm, perhaps ideas, discipline and other modifiers should come into play when deciding AT gain from battles?
"Walkovers" aren't supposed to provide large gain to AT, but maybe winning against a more powerful force in terms of quality, or in an even force during a long battle, should provide bonus AT? I'll need to agree that practice does help, atm the bonus isn't too bad, but it could use more variation during important battles where no side had a clear superiority from the start. Meanwhile the siege bonus is ridiculous, so maybe buff the gain from battles for both sides (Especially when most of the countries' armies are involved) and nerf the one from siege?
Tell me, why do you multiply entities beyond necessity. Very simple expression "military tradition", the value can be found in the dictionary and it will be close to what it means in game. Little morality, its a little faster recovery, a little faster recovery of manpower and a little faster siege. And military leaders

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Dictionary? Dictionaries generally are about the meaning of words, not terms like this. I have searched on the internet and the dictionaries I own, but no, nothing. That said, I must also point out dictionaries would differ from language to language, there are words with synonymous and meanings radically different in different languages.
That said:
Link to wikipedia; That's the closest thing we can get to a "dictionary" with the meaning to Military tradition, and nowhere does it affirm that you are correct in that "military tradition" is "tactics". The closest thing that the wikipedia article mentions is possibly what we can call the morale bonus.
And for your military reforms have a clear line in the game: military technology and ideas. Only they can dramatically change your army, after which it will be able to win. A tradition that's just a bonus, a small but nice.
Small but nice? I've suffered stackwipes with 3-4 tech advantage because I was careless and allowed an enemy to engage my (Numerically superior) army with their godly general. This happened today, mind you.
And now the answer to your question - in the game world is simple, no one survives. All died. Sad but true

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Oh, pardon. I did not know you were a dev and responsible for telling us poor players what terms and events in the game means with such assertiveness.
Hmm, on a more serious tone: No. AFAIK that's an abstraction, which is something that Devs have said they do to several things in the game. I believe that a decent system for prisioners would require a lot more coding, so if I am correct it's probably not on the agenda for EUIV.
Have you, perhaps, ever disbanded a regiment? Did you notice the manpower does not go back to your pool? Are we going to assume that your disbanded regiment simply disappears from the face of Earth, leaving no trace of their existence behind them?