As I understand it, the difference is that Wat Tambor is granted 100% turn meter, while Han is granted a bonus turn, although it's also possible that they had some sort of flag before that broke the "bonus turn" tie. They're not using the old system for breaking ties, so if they did have such a flag, it obviously is unrecognized by the new system.
Since bonus turns come before other turns, and since Han is normally the only one with a bonus turn at the beginning of an encounter in most battles and events, there wasn't a problem (bonus turns can be earned by other characters, but aren't granted at the very beginning of the battle).
However, there are PvE battles where bonus turns are granted. In that case, the first tie breaker is now TurnMeter, and if TM is the same, then the second tie breaker is the Speed of each toon, and only if TM and Speed are both equal do they use RNG.
The answer is easy, of course, grant Han +1000% Turn Meter at the end of each encounter and THEN grant everyone their bonus turns at the beginning of the next encounter. Han's bonus turn will come first since the tie between bonus turns will be the toon with the most TM and then his speed will be irrelevant. A situation requiring this kind of tie breaking hardly ever comes into play, but when it does, this will fix it.
Since they said they'll fix it in the future, I assume that this is (approximately) the fix they're going to implement.