It's on the todo list for the next version (whenever I get around to it), but not a 1:1 mapping. In my mind they are distinct: Martial Education is theory, combat traits are practice.
Despite the fact that the strategy employed in PB is not ideal for role-playing purposes, it is pretty integral to actually feeding the duel engine combatants with an appropriate combat trait in practice. Since the AI (and the player's own liege levy subunits as well as default leadership assignment for units) assigns combatants (leaders or subunit leaders, the only characters actually subject to an on_combat_pulse) from their court (incl. themselves)
according to martial skill, the vast, vast majority of characters that could ever be subject to a battlefield duel must have a martial education anyway. PB uses the same rule as ClearCombat for subunits getting a commander: all the time, no matter what the vassal opinion (very important), so it's further obvious. I've recently collected the statistics to confirm this in PB. It's disheartening, as other factors should affect commander assignment; martial skill certainly isn't the only major factor affecting combat tactics / chances of winning a battle.
Ergo, if a character's combat trait is ever going to get used on the battlefield (obviously the main application), either they must be a player with the ability to manually assign themselves to unit command regardless of their relative martial, or they must have a high martial skill (and, thus, a martial education, assuming no serious fiddling in the ruler designer / console). I recommend that you take this into account with any planned initial combat trait assignment events.
Speaking of which, I've been scoping a project I've affectionately named ACTA (Adult Combat Trait Advancement) for PB. If I ever do it (currently just at the data-gathering stage for calibration, using large sets of time-series savegames and an instrumented version of PB which maintains counters for every combat pulse, random sampling of combat pulse, battle won, battle lost, battle won leader, battle lost leader, battlefield duel outcomes, and feast duel outcomes-- rather dry and moving slowly), then perhaps you and I should work to integrate its XP system and trait advancement directly into the duel engine. As it stands right now, my main blockers are the difficulty in getting a decently deterministic profile of those counter statistics per character per time (that is, with the goal of truly balancing advancement for the AI so that, above a certain percentile of combat activity, average AI eligible characters advance at a predictable rate toward their possible combat trait level-up which can be easily tuned and observed). Frankly, the statistics are killing me (way too many dimensions and samplings of already-sampled, dirty distributions, despite the hundreds and hundreds of years of collected, instrumented data), so I may just jump into the implementation somewhat blind so that I can measure higher-level statistics like actual combat trait advancement success, but either way, to keep to my standards at least, I'll still have to return to those lower-level statistics for verification and tuning rather immediately after a first-draft implementation.
FYI:
The implementation will be of scope mostly limited to plausibility. For example, it is only possible to climb so far up the ladder, relative to your starting point (combat trait at age 16), and XP points (measure of progress toward level-up) are earned at variable rates, modified by factors like age and an associated ambition being enabled, with a different base XP gain for each type of "combat activity," with things like successful duels being weighted much higher than the more frequent and less momentous impulses from participating in battles / leading armies. This will actually be accomplished with CK2's limited variable support (no arithmetic); a script will generate all the possible modifier combinations and generate the code to evaluate which of the possible combinations is true and then add a pre-calculated floating-point value to an eligible character's XP variable upon different types of "combat experience impulse" events. First draft slated to only include hooks from battle-related on_actions and duel engine output.
Again, it's still effectively just an idea. The nice thing about a "scoping phase" is that you can decide the project's not worthwhile or feasible after all.
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