Yes, I believe mauve is the proper colour. It's usual to see this alongside the EUR designation, or sometimes FHUG. I guess they used the same multi-language box for the whole of Europe, hence why it's not a country-specific release.
Typically UK releases should be a dark green with a UKV designation. Other countries each have their own individual colours. For example, I believe France has a dark red triangle. Scandinavian games typically have a greenish-yellow colour and SCN designation
The only two we should ever have in the UK are dark green and mauve. Any other colours and they're European imports
This dark yellow is a new one to me though, and even more unusual that it also accompanies the EUR designation. I don't understand why it's not mauve like the box flaps though?!
The standard UK release has a dark green spine triangle, as you would expect for a UK release