There is an essential difference between the SPK from Kastelo and SynoCommunity. The SPK from Kastelo is a closed package with each final version, which has to be installed on the Synology as Update. The SynoCommunity package only makes major SPK updates, such as from v1.7.1 to v1.15.1 currently and the updates from final to final are made internally. However, this has the disadvantage that structural adjustments in the software may result in malfunctions.
For the record, there aren’t supposed to be any such structural adjustments that we don’t account for, or auto upgrade would break for other users. So I wouldn’t worry too much about that.