The Cubase and Nuendo plugins were created to make Stream Deck configuration easier by reading Cubase and Nuendo files and filling the plugin with key commands and Generic Remote settings from Cubase and Nuendo. However, because of updates to Cubase and Nuendo announced by Steinberg, these plugins will eventually stop working.
Steinberg has announced that the Generic Remote device in Cubase and Nuendo will be removed in a future, unspecified version, and when that happens, the MIDI part of the plugins will cease to work.
Steinberg has changed how key commands are saved to the configuration file (and thus made available to the plugin) in Cubase and Nuendo 13. When key commands are modified, the configuration file isn’t updated until Cubase is restarted. This change means that whenever you alter a key command in Cubase or Nuendo, you must restart the software for the change to appear in the plugin.
Using the plugin’s key command feature will still be available, but I believe the original goal of simplifying things is no longer achieved. The Stream Deck Hot-key plugin makes sending key commands easier, removing the need to restart Cubase/Nuendo after making changes.
Since the original design goals are no longer valid and the MIDI part of the Cubase and Nuendo plugins will eventually stop working, the plugins will no longer be developed or maintained.
Of course, you’ll need to decide whether to use the MIDI part of the plugin for the remaining time before Steinberg removes the Generic Remote. The same applies to the key command feature, which still functions but has become more cumbersome due to Steinberg’s changes, requiring a restart of Cubase/Nuendo.
My recommendation, however, is to consider switching to the MIDI plugin instead. The MIDI plugin provides many more features than the Cubase/Nuendo plugins, and it is future-proof, maintained, and continuously developed.