Tobias:
Here is a hypothetical example to highlight different folders and tagging within MC.
To display/change tags within MC, do the following:
1. Select your Artist view (Artist 1).
2. Select a particular artist. In my case, I selected Elvis Costello (Artist 2).
3. Select a particular album or albums. In my case, I selected two albums, "My Aim Is True' and 'Armed Forces', to simulate your situation of two folders (Artist 3).
4. Select all the tracks of the selected albums (Artist 4).
5. Select the tagging action from the Edit menu: Edit > Tag (Artist 5).
The tags for the selected tracks will appear to the left in a vertical arrangement. Note, because two albums were selected, the value in Album is [Varies] but notice that the Artist for both albums is 'Elvis Costello'. If I select one album, either one track or all the album tracks, the Album value will reflect the name of the album, 'My Aim Is True' (Artist 6). Let me know if this helping or hindering.
By the way, tagging all the tracks that you want to have one particular value, such as 'Van Morrison' in the Artist field is quite easy. Select all the pertinent tracks of the albums in question. Then, via the Tag function, Edit > Tag or keystroke combination Alt-Enter, change the Artist field value, and press Enter. The Artist values for all the selected tracks will be changed in the MC library. The metadata change will also occur in the physical file. If you change your perspective and think about MC as your primary database, that may help with your understanding.
Cheers,
Lawrence