i have been keeping carpets for 15 years, and with many trials and errors, and with many losts......etc.... let me tell you, i have seen litteraly dead anemones come back and healthy. i want to let you lknow this:
the less you mess with the tank, the more chance the new anemone has to survive.
by doing more to your tank, it means you are asking the anemone to do some more adjustments. all of the preparation for a new nem should be done BEFORE you recieve the nem. once you acclimate it to the tank, leave the tank alone and let nature do it's thing. if your nem is not healthy enough to bounce back, doing more won't change the outcome.
so now, my suggestion is you adjust the flow so that the "area" is calm and not turbulance. this will help the anemone settle down, and also prevent the nem from being blown around and eventually end up in the powerhead....etc. other than that, leave the tank alone. if your water parameter is good for other inhabitants, then it should be good for your new nem.
Best of luck and i hope everything will turn out fine for your nem. dont be going crazy and doing all kinds of adjustments/changes because you will not be able to alter the outcome....... and it doesn't matter who say what....