Yes, your new plaster is curing and will be a source of acid demand for a long time. For some, it can take almost a year before the acid demand starts to level off. During the winter months when the water is cold, let the CSI remain in the positive range (0 to +0.1). You're really in no danger of scaling and keeping the CSI a little on the positive side will help keep acid usage to a minimum. Also, if you have any water features (I think you have some sheer waterfalls or deck jets and bubblers?), stop using them or minimize their use as much as possible. Aeration of the water will cause your pH to rise very quickly and add to frequent acid additions. Once you start using the SWG, it too will add to the aeration of the water and cause upward pressure on your pH. So expect to use a lot of acid in the near future.
If you post a new series of test data (include CH), I can try to see if there's anything that stands out to me.