If you read further up in this thread you’ll find an explanation. I just ran into the same issue.
I understand the reasoning behind including 聞こえる in the ‘potential’ grammar point. However, I do wish it was mentioned in the grammar summary. Because now I am finding out about this exception in the review and I only managed to find out what’s going on with this question because I saw this discussion. It’s not very intuitive or user-friendly. @mrnoone
I have decided that this example will be replaced with normal one, and 聞こえる plus 見える deserve grammar point on their own!
And add additional information in warning section!
Thank you for informing us how unintuitive it was!
In the example and question " 私の好きな映画が 見られたら いいね"
Why is it just 見れ or 見られ? Why not 見られる?
does it have to do with the grammar point that follows?
It’s because of the conditional context ら for “it would be good if…”, ‘hope’ is just smoothing out the translation. They put the link for たら on this sentence, this will explain it best.
Why does 見つけれなくて not work in 見つけられなくて すみませんでした。?
I see that 見つけれる would be the casual form, but since the question is looking for casual, there must be another reason for it.
@CrisH
Hey
みつけれなくて has been added to answers!
I have removed the “casual” hint. It was an error in this case. Also, by “casual” we usually mean the short form (not ます・です - long form).
By the way, remember that らless potential forms are considered by some speakers to not be grammatically correct, so be careful when using them.
Sorry for the inconvenience,
Cheers!
Ah, I see. Thanks 
The language in this warning is confusing:
Great! However, remember that らless potential form is considered to be grammatical error by the number of Japanese speakers.
It took me a while to figure out that “らless” meant “the potential form without ら,” and not “ら (the less potential form).” Would highly recommend changing this!
@petepolack Thank you for your report! I have updated the hint to read: “Great! However, remember that ら抜き言葉 (words that omit ら) is considered to be a grammatical error by a number of Japanese speakers. To avoid issues, it might be better to avoid it, especially in polite (です・ます) speech.” Cheers!
I just ran into the exercise 私わたしの好すきな映画えいがが みられ たらいいね. It seems weird to me that an exercise for an N4 grammar point would use N3 grammar (たらいい).
@Johnathan-Weir I believe the confusion comes from a poor translation on my part. The subject of the sentence should be “I,” not “You.” Cheers!
In “ほしいけど、お金がないから買えないですよ。”, why must it be informal? Because of the です? What is the です doing there anyway?
Basically yes. The formality comes at the end of a sentence, and you only need one indicator in a sentence that it is formal. Please don’t think of 買えない as informal, but rather as plain form.
Both 買えないです and 買えません are perfectly acceptable, but 買えませんです is too much.
Thanks! But what’s the grammar that makes this plain verb + です work? Is there a Bunpro grammar point for it, or do you know any other website that explains it? I don’t think I have ever seen that before.
I think it would be difficult to create a dedicated BP grammar point that is specifically aimed at avoiding a common mistake. We know from this grammar point that です makes something polite, and we know the meaning of ない from here. I don’t know… I just feel like creating separate points for ないです, なかったです, etc. would be difficult to implement.
Maybe a note could be added to the です grammar point that it can also be used with negative verbs? It already has one for adjectives.
There also is the じゃない grammar point that doesn’t mention です but actually has example sentences that use it.
Since this is kind of an exception for です where it doesn’t actually have a grammatical purpose and is only used for politeness, a dedicated grammar point on informal politeness or something could be focused on that? I don’t think it has to be different grammar points for each individual case. A lot of people seem to simply consider です a polite version of だ in the beginning, but that’s not true in modern Japanese, so IMHO it makes sense to highlight this.
@testing please note that this is not “plain verb + です”. It’s specifically negative forms (-ない) or い-adjectives or other words that act like い-adjectives where this originally ungrammatical use of です is now established as a less stiff way to make a sentence polite. In the じゃない grammar point I found this stackexchange post that has some interesting comments on nuance. This page on imabi.net goes into a bit more detail as well.
