You can add and download the FME Hub custom transformer by searching for keywords, as well as adding a general transformer, Once you have downloaded the custom transformer, FME will always use the downloaded local transformer. Even when the custom FME Hub transformer is upgraded, the user will not be notified of the upgrade.
I suggest that when you add a transformer that is downloaded from the FME Hub, If the FME Hub has an updated version, the upgrade prompt is displayed in the transformer brief.