Considering they all have explanations now, we thought that it would be better to put へいく before へ, simply because if we had done へ first, most of the examples would have been へいく anyway. Seeing as that is the most common use of the へ particle.
So we figured that へいく was technically the easier of the two, and then we could expand the particle usage by itself a bit later, at the same time as we introduce other verbs that can be used with it.
Good point on the え! I will include it 
Just giving a heart to the original post was not enough to show how much I appreciate this update.
Hi,
I would just like to take the time to state that the grammar explanations are the killer feature for me. I started with Bunpro a few months back, before grammar explanations were introduced. At that point, I liked the site, but I was on the fence about a long term subscription. Reading external references to understand the grammatical points was fine, but cumbersome, and the quality of the linked references vary.
Then explanations were added, and the value I found in Bunpro went through the roof! The write-ups are clean, convenient, easy to follow and just thorough enough. It really elevates Bunpro to a whole other tier of japanese learning tool. But a few days ago I hit N4, and with the lack of explanations, I’ve been doing one study session per 2 to 3 days instead of every single day. I am once again on the fence about a long term subscription.
So I do hope those N4 explanations make their way in soon! Great job on the site, and thank you for all of your hard work.
At the moment, we are looking good to have N4 ready to go by mid Jan (ish). Hopefully you find the N4 writeups as helpful as N5.
This one is a little but harder to predict, but I would like to say mid April at the latest (if we don’t get stuck on any other projects).
Thanks! I’m about to finish N4 in a few days so I was curious.