They chew out the extra cocoons to keep the cell size at 4.9mm
That is true not at all. Bees make "natural cells". I ahev measured them in my hives 5,3.
When combs are old or moldy, bees chew them away and make new and they are 5,3 if they are used to build that size. If they use to build 4,8, they do it.
It is not universal order that bees want to make smaller cells than beekeper. In most countries it is measured 5,3 mm.
Bee breeding started when man invited frames. So it is possible to change a queen and selcet queens.
Great progress arised when man started to use instrumental insemination 60 years ago.
When man has selected productive bees, the size of bees has grown 10%. It is same with Apis cerana.
If you follow the course of domestical animals, they are not same as in nature.
Some have become smaller. Finnish reindeer is smaller than it's wild relatives. Russian reindeers are figger than Finnsih.
Salmons are now smaller than before because net fishing catches biggest salmons first. So, Salmon is regressed. 90% of our salmons in nature are man breeded.
When you live among other beekeepers, it is difficult to keep own strain of bees. That is why I suggest that don't waste time with that matter. It is vain effort.
When we had 20 years ago feral bees (german black) it was really difficult to keep yard in satisfactory condition. Those mad ferals were so quick in mating that most of new queens had german black workers. - Awfull. I nursed them 30 years. Nothing good to say, but it was that time. Then Varroa killed feral bees. I have not seen them for 15 years.
In Tasmania there are very mean German Black feral stock. It have not changed even if Italian have brought tens of years to Tasmania.
German Black was the first race which was brought to USA. Do you have them any more?