On Goni Peninsula, all them change their extension randomly. I think it has to do with the random flow. I have my gyre set at alternating waves from side to side, but also randomly spiking high and low.
So all the gonis act differently and at different times depending on the flow. Sometimes they are tightly bunched and extended low like a buzz cut. Sometimes they are wavy and random and long.
The lighting level is a bit much, admittedly, around 250-300 par but I have a maxima clam nearby. I always acclimate them to the 200 ish range starting with 100 if I procure a new one. I would recommend lower par in general unless you have a light lover like a clam next nearby. But gonis can adjust.
They are rarely spot fed, only when I'm bored. They soak up alk and calc so if those aren't higher for their skeleton ball (or encrustation, depending on the species) then they will grow slow or not at all.
Goni's are easy. Especially the aquacultured fragged ones. Your' gonis fine. As long as their polyps aren't retracted completely into the ball for days at a time. One day is fine. Over a week of no polyp extension however, then you got problems and expect receding tissue soon if it has gone that far for a week or more. Check your water parameters or light.
Change your flow depending on how you like the polyps, long or short. They will adjust their polyp extension to match the waves. You don't need a specific water flow type to raise them. Gonis are like cats. Sometimes my gonis retract randomly, annoyed for some reason for a few hours. Sometimes a day. Maybe Mr cleaner walked all over them. Maybe willie nipped one trying to get a baby aiptasia near them. Who knows. I wouldn't worry. Keep your alk calc up, and all the other basic parameters in check, they will be fine.
I don't have a skimmer. I'm thinking of getting one out of boredom. But goni's don't mind a little nutrient rich water.
Here's a quick shot I just took. See how all the goni's and alve's have random length extension of polyps? Some are short some are long. Even ones of the same species! They even change on some days. It depends on the flow, since my flow is a bit random. Except for the encrusting ones. Those are always low polyp extension with micro sized polyps.