The slightly raised "two opposite ends of the mouth" you're seeing are probably the anemone's siphonoglyphs, structures which facilitate bringing water into the anemone. It's fine for them to be slightly raised. You can clearly see the right-side siphonoglyph in the picture I posted earlier.
With the caveat that I'm not confident there's any particular things you can do that will affect the outcome --this anemone may just be one of the ones destined to make it or not-- I'll offer what I would do if the anemone were in my care:
First, I know of three reasons why anemones deflate:
1) To achieve osmotic equilibration with the surrounding seawater. This reportedly takes from 3-6 hours after a change in salinity. So, it's likely no longer relevant in your case.
2) As a defensive maneuver so they can retract under the rock or sand.
3) When they're attempting to expel wastes.
I'd assume the anemone is still trying to get "stuff" out. The S. haddoni anemones I've had that fully everted their "stomach" had little brown specs of "stuff" in there. When those floated away, the anemone would pull the insides back in and then reinflate. That's not something you can help much with.
But, it can influence what you choose to feed. The anemone is going to store each piece of food you give it in different "folds" (mesenteries) within it. There seems to be a lot of effort involved in mechanically getting the food in and the waste back out.
At nine days, IMO, the anemone has had plenty of time to adjust to your tank conditions. So, I'd start trying to feed it. Specifically, I'd provide a very limited number of pieces of food (probably just one), shred it so it has much surface area as possible, and fortify it with something like Selcon. Hopefully, that would enable the anemone to get as much nutition with as little effort as possible.
Likewise, I personally wouldn't cut back on the lighting schedule. Many S. haddoni anemones come from shallow regions, some so shallow that they are exposed during low tide, and such areas have extremely high lighting compared to what is in our tanks.
I've put a number of newly acquired S. haddoni anemones in a shallow tank, inches below a 250W MH fixture in an area which produces PAR readings around 500 decreasing radially outward. If there's just sand in that area, they move to find rocks. Once achored, they stretch back towards the higher light center.
FWIW,
Mark