Translation:We are going to Bordeaux in order to buy some red wine.
Bordeaux with a capital B is a singular city. But if you use bordeaux with a small b then that's the word for claret. A particular type of wine. The word bordeaux can also be used as adjective for the colours maroon/burgundy. So using the small b rather than the convention common to both French and English of capitalising proper nouns, was indeed wrong. Though the reason Duolingo gave for it may be a little confused.
It wouldn't be standard English. Some dialects might have 'We are going to Bordeaux for to buy some red wine' (That's a common scottish construction) or perhaps 'We are going to Bordeaux for some red wine', but not 'We are going to Bordeaux for buying some red wine'.
The drop down menu has "Bordeaux" or "burgundy" but these are two different (competing) wine regions with different types of grapes for both red and white wines and very different styles of wines.
So is this a mistake in the drop down tips or do the French really mean 'burgundy' in some contexts when they say 'Bordeaux'? Sounds weird to me.