Yep, the colour coding is consistent, no matter the user. The 2 pronounciations just seems a bit random. Would they have put scone there?
I think that the colour coding is meant to go green - easiest, yellow next easiest, blue next, purple last.
The issue with the purple here is that at least one word only has a second pronounciation as regards one specific American pronounciation, and that accents might lead to different pronounciations of a lot more words.