The article is interesting! However, some thhings are not clearly described.
It is understood that, for Favourable Pressure Gradient which is positive Pressure Gradient towards downstream and Separation of flow does not occur hence no reversal of flow. The opposite is true in adverse Pressure Gradient. This can be achieved by changing the shape of the body, i.e. the dolphin's fin must be changing.
There might be some more things other than this to the anisotropic compliant wall. That need to be described in detail for a common reader.
Overall, the article is good and informative.
Thanks and regards.