Lebkuchen

09:11 Aug 22, 2020 

I'm not sure about that. While being roughly biscuit sized, I think they have a definite cakey texture. Also, ginger biscuits are a distinct thing in the UK. I'm not sure about ginger cookies in the US.
I think we might have a jaffa cake type controversy on our hands if they tried to classify Lebkuchen as biscuits. ;-)

See also the following text from: https://www.cronertaxwise.com

VFOOD6200 states “Lebkuchen are small pieces of chocolate covered gingerbread, these look similar to sweets and are often packed like confectionery but are in fact small cakes.” Therefore, Lebkuchen are zero-rated.

12:25 Aug 21, 2020 

I know Wikipedia says Lebkuchen are "similar to gingerbread," but that doesn't seem quite right, at least in my experience. When I hear the word "gingerbread" by itself I think of gingerbread cake, and if you google just the word "gingerbread," your top hits will be mostly cake recipes. But Lebkuchen are really more similar to gingerbread cookies (AE) / biscuits (BE), and that's what I'd suggest you call them in your explanatory note – or just "ginger cookies" / "ginger biscuits" if you're pressed for space.