Frerichs seems fairly unpredictable with her two best steeple results (London 2017 and the recent AR) far surpassing anything else she has done. Coburn seems overall more consistent with at least some 1500/3000 flat or indoor times that fit with her steeple result.
However suspicious one might be about Kepkoech's 8:44, it basically is the difference between a sub4/8:25 flat runner and a 8:40-50 flat runner (like Coburn or Frerichs).
But a woman capable of sub4 and 8:25-30 usually has little incentive to do the steeple in the first place because she will be top3 in her nation and top10 in the world over the flat distances. So women's steeple abounds with 8:45-9:00 flat runners. I think that there will be more times around 9:00-05, but sub 8:55 will remain outliers for quite a while.
If more women keep running sub/around 14:30 5k times, we might see more 14: 40 runners trying the steeple and accordingly faster times. If, as others think, due to stricter controls, 14:30 and similar times become rare again, the steeple will also remain slower.