Eventually, yes. Both cells will average their soc.
But you're forgetting that reading the average voltage does not mean that each cell is actually that voltage.
If you take a look back at the chart I posted you see there is a time factor to this assumption you're making where they do not immediately converge in voltage. This is exaggerated by the very properties of lithium cells that make them desirable. Two cells at different SoC may hit the knee at different times and if they are not able to self-balance before the more full cell is itself full the potential to overvolt still exists within the group, however short a duration or or low the overvolt delta actually is, it can still occur.
If one single cell in a 4s pack can overvolt even though you're at 14.6v, and it can, then a group also can. It's possible to overvolt a single cell at 14.4v too, or even much less, but you should know that also.
And if a group can overvolt, then it's possible that a single cell in that group reaches full charge first, the bms continues to allow charging, and the overvolt situation occurs despite being undetected strictly because it's averaging that extra voltage out to a lower value.
The lower cell will drag that group down even though the pack/charger is presenting sufficient power and voltage to overvolt the full one.
Just like how 14.6v/4 is still only 3.65v per cell and yet somehow magically it's possible to exceed 3.65v on a given cell in a 4s pack, sometimes significantly without protection in place. The potential is still present.