I GOT IT WORKING
For everyone who is interested in this topic. Eventually, I got it to work. The X Touch One needs to be added to Cubase as a Mackie device and in MC Cub mode. In this mode, every feature presented on the Cubase template for the device functions as intended. Make sure the MIDI ports are assigned appropriately as well.
Based on the specifications given in the official device documentation, design the surface that best fits your needs. Next, tap the device’s Master button. At this point, Cubase will automatically produce two knob controls when you touch and slide a fader. A pitchbend control is one, and a touch control is the other.
Choose Plug-in Window Focus Only under the Quick Control Focus options. You can now begin mapping plugins. Simply press the master button to enter master mode, which releases the fader control for your use, to use the fader with plugins. That’s it.
To illustrate, I set up an EQ plugin, which has several fader controls, by making several pages, one for each fader. Additionally, I assigned the F1 and F2 buttons on every page the Next Page and Previous Page functions. This lets me navigate through fader controls on the plugin. Multiple plugin faders can be controlled by a single fader device in this manner. Remember that every control assignment has two focus options, so make sure to make it global.