We've decided it was time to address this: it is pronounced [ˈɑːkɪ] [nəʊd]; the same way you would say 'archi' in archi-vist, for example, in your native tongue.
So in french, it'd sound like 'ar-she-node(s)' and in english it'd sound like 'ar-kee-nodes.' Feel free to alternate between these two, but we would like you to take this opportunity to really understand the concept: archi-nodes brings the prefix 'archi' to the noun 'nodes,' which together form 'archinodes.' It's cute, we know. Took us about 4 years of brainstorming to finally decide on this clever combo, so we are sticking with it. We're not totally sure why it's such a hard word for people to get 'right,' and while we're open to all the possible versions of 'archinodes' out there, we don't want to hear arachnodes anymore.