"Next week VW releases its delayed annual report , giving some indication of how much more the whole saga will cost-difficult, with no American deal . " Cost-difficult, does not mean anything, it is not a word either. Instead, it means that VW will release a report giving an indication of how much the saga will cost. the "-difficult" part is used as another sentence. Think of it like this: This will be difficult, with no American deal. So to sum it all up: how much more the saga will cost, which will we difficult, with no American deal. Here they just use the dash.

It isn't 'cost-difficult', as in a hyphenated word. It should be read as "...giving some indication of how much more the whole saga will cost - [This will be difficult ] - with no American deal.

This is not a compound noun. There are some missing words in this text between "cost" and "difficult". You would need to find the whole text. It's not possible to make overall sense of the text as it is now.