I can think of three factors that can mitigate the outside bean texture, and using these factors together or individually can give you the boost the beans need. But none of it matters if the roast smells great and tastes how you like in the cup.
My observations so far for the physical phenomena is that the outside cells swell and puff out, the lighter part is actually more cooked than those darker parts. Once the bean is smooth the ending temp has the most significant factor on the bean color and can by altering adding energy to the beans in the yellow to brown phase. Beans adversity to taking on heat is its density and moisture content so an Ethiopian high grown is much easier taking on heat. A low grown Brazil would be it’s opposite but funnily enough if you have a Guatemalan which is spongy yet has a lot of water this requires a lot more energy in the beginning. So the bean characteristics are always the basis for building the profile.
Increase speed, via ROR during yellow to brown. This ramp up creates enough energy potential in the bean to expand. For me this is roughly the range between 360F-415F which yellow can start, to 420F-455F where brown starts (Based in Marshal Etheo style profile). Sidenote*
Increasing conduction (lowering fan).
High sustained inlet temp will inevitably push the beans though the stages so the beans can build this momentum.
*For all beans; basing the color phases on time duration is a decent way to build a profile. Meaning input temp is based on how long it takes for the beans to go through green/yellow/brown/1C+dev/2C+dev.