This may or may not be the approach we’ve already taken in the draft of this write-up 
(By the way, the items on the list up top are more of a rough guide to what we originally wanted to add based on suggestions. So subject to change, etc. I will make a mental note to update the list after the next update)
「形容詞・形容動詞」＋ことといったら、～。
The “Try!” textbook series lists this as N3 grammar.
Thanks for the suggestion! I’ll add it to the list for consideration.
(word)の(first letter)の字もない ー not a shred of (word)
For example:
人情のにの字もない
反省のはの字もない
Don’t see やっと mentioned here yet. Always thought it was weird とうとう, いよいよ, and 遂に all got grammar points but やっと didn’t despite being the one I come across most often.
Since it is already mentioned in the
verb(ます)-stem +にくい
maybe it would make sense to add
verb(ます)-stem +づらい(辛い)?
Or as a variation of にくい?
Edit: Found it in the update list. ^^
That fact that it is the most common is basically the reason it isn’t included in a lot of grammar resources, and is just considered vocab. I’ll see if we can add a link for our やっと vocab entry to the other ‘finally’ points. That might be a good stop-gap measure.
Is there a grammar point that covers をして/をしに that I just haven’t come across yet? I don’t see it as its own point (are they even the same point? I can find a lot more on をして than on をしに on Google). It seems like it’s very formal/literary so might not be high priority, but I’ve seen both used in example sentences so might be good to include.
Can you give some example sentences of the usage your talking about specifically? I am guessing you’re talking about をして being used with causative expressions but just want to check what you mean. Any examples of what you have in mind would be greatly appreciated!
Yes. Unfortunately, I don’t think Bunpro lets you search for text in example sentences (which would be nice), but this specifically is what I mean: をして - Wiktionary, the free dictionary
Did a quick search and I don’t think anyone has mentioned it yet, but it would be nice to have a write up for ～ばと思います.
I see it used quite often at work and it threw me for a loop the first time I saw it!
I’d like to suggest the following but I noticed it’s not really listed as a grammar point anywhere else
noun+日和
A good day for ~~
I learned it as a grammar point in the textbook Dekiru Nihongo but it doesn’t seem that widely listed elsewhere so I understand if it’s not of great importance/worth being added, but just thought I’d mention it!
Haven’t seen 又は mentioned. Unlike やっと in my last post, I haven’t seen 又は outside of the N4 vocab deck. It seems relatively synonymous with the か grammar point meaning or (aside from formailty/politeness I’m guessing), but there’s no relation mentioned between the two, and when adding 又は to my reviews it’ll flag か as outright wrong. At the very least, expanding the summary of 又は to distinguish the two would be helpful.
～によりけり＝～しだいで決まる・～によって決まること
手引き：ゲームのルールも場合によりけりであるが、人死に厭わないものだということだけは、確かである。
これをただの偶然で済ませるかどうかは人によりけりだが、俺は引っかかっている。
It would be helpful to have the たり (N5, Lesson 7) expanded and have adjectives included. (Only mentioned in comparison to や)
I think I did not see this in the list above.
Grammar point from my school’s textbook that bunpro does not have outside of a couple of uses as individual vocab words:
[た]ものではない - Impossible to do
Indicates that something is not worth doing, not good, or unbearable. Often
conveys a strong negative opinion or dissatisfaction.
The textbook labels it as N2 as well.
Example sentences (this is copy-pasted from the textbook, so I’m not sure whether or not it can be used by Bunpro officially)
こんなまずい料理、食べられたものではない。
こんな料理、お客さんに出せたものじゃない。作り直して。
この映画は、演技がひどくて見られたものではない。
One grammar point that I thought used to be on the app but seems to have disappeared is "付き"but I can’t find it anywhere. It Means “included/with” and is derived from the verb 付く meaning “to be attached”
Examples
駐車場付きのアパート - An apartment with parking (Included in rent/deal etc.)
As opposed to
駐車場があるアパート - An apartment with parking (Just states the existence of there being parking available, Not necessarily guaranteed with the apartment
保険付き - With a warranty
朝食付きの予約 - Reservation with breakfast included
etc.
I’m no expert but I think this would be quite useful from N3 onwards
Had this come up when I was reading earlier and didn’t find it on bunpro.
お宝を横取りしようったってだめだよ
I did find the grammar point in the Advanced DoJG on page 597 under (っ)たって (2)
I can see it fitting into one of the other grammar points as a note, but it would be great to have it on here, especially searchable
suggestions:
明け meaning the end of something, like 夏明け (end of summer) etc. I see this fairly often in books so I think it could be a useful grammar point, but then again I guess if you added every single possible suffix as a grammar point we could be here all year… Maybe this one is self explanatory enough already? IDK just thought I’d throw it out there 
ETA: the reason I’m also suggesting it is that it’s kind of confusing at first glance, because I always assume it would mean the start not the end… and it also does mean the start… help
I would also like to see そびれる | Bunpro as a grammar point. The description is “to miss a chance to do, to fail to do, after the -masu stem of a verb.” To be fair I haven’t seen it that often but it did throw me for a loop.