The coreFX plugins are for both an object or track. They accessible by:
Right clicking an object and selecting Object Effects
or to apply to a whole track
From the main timeline or the Mixer - click the FX button in the track header, this will open the Audio EffectsTrack panel
Select the + button at the bottom left of the panel - located where the arrow in the image below is pointing - note in the image it is hidden by the popup menu which will open as shown below.
Select the Magix plugins option - you will then see the coreFX options to choose from.