Let me preface this by saying that I cannot read any Japanese at all, so this is all from Google translate. Bold text is the current thread titles on the front page of the Japanese General Discussion forum.
Let's write indifferently the implementation and want to emote ( '· ω · `)
25 pages. Appears to be an emote suggestion thread.
Attrition to write a carefree requests / suggestions / delusion
524 pages. This appears to be the more general suggestion thread, for any ideas anyone happens to have that aren't covered by a more specific suggestion thread.
Set meal
13 pages. I think this is a thread that's discussing the lack of innovation between ARR and HW and lack of depth of content, especially given that someone linked to a reddit thread titled No, it's not you, the game in its current state is boring. They also preface the think by saying what appears to be something to the effect of "Yeah, it's a foreign website, but a lot of JP players feel the same."
Seoul Crystal equipped column in the avatar frame
1 page. I think someone is asking for visible cloaks/capes, and trying to preempt the likely arguments against them.
FF14✕ specter watch collaboration event impressions attrition
38 pages. Yo-kai thread. Second post translation: "It is all messed up feeling because of FATE."
Chat thread
476 pages. First post translation: "It is a chat thread that targets the entire world of players"
For Sukusho of other games
2 pages. I think this one is discussing people using their lodestone diaries to talk about games other than XIV.
,,, The content finder is hard to match
2 pages. A thread that previously consisted of a single post after the 9/4/2013 maintenance, at which point someone noticed that DF was taking longer than before the maintenance to form a group, and necrobumped by someone on 8/20/2016.
Thread to write the figure of the future "do not want this happens" Final Fantasy XIV
67 pages. The premise of the thread is that it's a place for people to post about things they don't want to see happen. Examples from the first page, which is from September 2014, include things like Maat appearing as part of an FFXI collaboration and Ninja being postponed until after 2.4.
- Bragging thread to talk about the play location-cute Raraferu of Raraferu
41 pages. This looks like it might be a screenshot thread, possibly with a focus on lalafell.
Why useless? Armor of Kyasuhira Mirapuri
26 pages. I think this thread is discussing glamour being restricted to armor that your class/job can already equip, particularly that casters can't wear heavier armor.
For the new generation VGA (such as the GeForce GTX 1080)
6 pages. Discussing graphics cards.
Reid Disrupt The number of disclosure and update
3 pages. The first post of the thread includes the graphics from the official Eorzea sentence that showed the Gordias clear rates. In general, the thread seems to be discussing that, although a number of people appear to be expressing frustration that without knowing the total number of subscribers, the number of clears aren't that useful.
Eoru THERE cafe
4 pages. Eorzea cafe thread.
Add and improve feature requests in Mentor system
54 pages. Mentor system suggestions.
Moruboru & Michael of English course
1 page. I'm not all that clear on what this one is about. I think it's related to Fernehalwes, possibly them wanting him to provide information about English, possibly also about foreign players and the localization process. This is certainly the one I'm least clear on.
Mira pre-collection!
79 pages. Glamour screenshot thread.
About Eternal band]
11 pages. A thread about the Eternal Bond ceremony, with the first post commenting on Yoshi-P saying very specifically that it's not a wedding/marriage, even though it has almost everything in common with one.
I want equipment of this look!
61 pages. Glamour request thread.
I want to save hairdresser hairstyle change.
1 page. A request to be able to save the results of using the aesthetician directly from that interface, rather than having to back out to the character selection screen to do so.
As other people have said, the Japanese forums consolidate threads more than the English forums, so even if we had similar numbers of Dev posts, they'd have a much greater percentage of threads with a Dev response.
They have a 524 page suggestion thread, where we'd be more likely to have 524 threads of different peoples suggestions.