" the point to doing the experiment was to demonstrate that changing environment can change physical structures without needing mutation to cause the change"

"Potentially an ancestor (to modern land animals) had that same plasticity, which allowed it to engage in new environments"

I see only semantic differences in these statements. The English language can be a bugger.

We're looking at academic science here. Well done for getting it published in Nature! But the point to academic papers is a) to get grants for the lab and b) to suggest topics for further research. As seen here three grants supported the lab. Presumably they're finished supporting this particular research. The potential further subjects are more interesting to me. I don't know what correlations were made to actual fossils (can anyone access Nature to actually look at the paper?). That would be one direction. Someone might look at amphibian muscle and bone structures of the shoulder and neck to see whether the changes observed after birth in the fish had become embryonic in amphibians. That would imply an actual change in DNA. Further along that line, a demonstration of the chemical change in the DNA active in the development of that structure would be strong indication of evolution in action. There may be other directions.

My point is that this study, interesting as it may be, is no answer but an inspiration for questions. I suppose some of those questions might involve God, but as Richard Dyson said once, "I'm OK with not knowing the answers."