I already mentioned it once, i think the big reason why light -heavy combo is awkward on halberd, is because these are horde sweeps, that both start from the same side. It impacts targeting of multiple enemies in one swing, or swing extension (with mouse).
With usual hordeclear chains on other weapons, they have alternating sides on sweeps, like greathammer:
i throw one strike, cleaving some dudes, extending with my mouse, then after that, my crosshair is already positioned perfectly to start a reverse sweep, and move&extend it in the opposite direction, bringing the crosshair back to where it was at the beginning. And so on you can repeat the sweeps, extending the strikes each time.
But with something like halberd, after the first extended sweep your crosshair would be on the left to your enemies (as usual), but because next sweep is also goes from right to left, you have to bring the crosshair back first, where it was prior to the 1st sweep, and only then start the new sweep.
In general, there’s no positive things about this light sweep -heavy sweep combo of halberd. Heavy sweep was just shoved there as a by-product of first heavy becoming a stab, imo.