You can extract one value n (starting from zero) from a multi-value tag-field x by ... $meta(x,n)
So you can display each single value in a listview column.
If you want to edit a single value in the listview, then you need a separate (temporary) tag-field for each single value.
Afterwards you have to collect all the single values into a multi-value tag-field, ...
then delete the temporary single-value tag-fields.
Read there ...
Automating Changes to Artist Values
DD.20140706.1757.CEST