I was recently checking out some of AIUE OKA's stuff and I saw that they had published some content for X - Eros #82 which features a pair of blonde twins. Though it was not a traditional chapter release. It appeared to be about 16 pages long with 8 of those pages being pure dialogue. I am not sure if this was some kind of special Japan exclusive content or not. Just wondering if anyone knows anything about it.
If you look at the contents page for X-Eros #82 you'll see that Aiue Oka is not listed, so at the very least it was not put in the magazine, which is the data we're given.
My info should be taken with a grain of salt as I'm not at all personally familiar with the Japanese scene, nor can I even read Japanese myself. But AFAIK...
The publishers sometimes like to include additional booklets and other inserts into their physical releases. If you look through Wanimagazine's listings, they seem to do this particularly often with X-Eros. In general these materials tend to not get included in any digital releases, either in Japanese or on FAKKU; for example #82 also includes an artbook with material by Mutya, which isn't available online anywhere that I know of.
However, #82 seems to be a bit of an exception in that they also had a pair of short booklets with work from Aiue Oka and Michiking, along with some audio recordings, and these did get released online; specifically, they were released as a separate item from #82 proper on dlsite. I don't know if that's something they did differently because it included audio and not just art. I suppose in theory maybe FAKKU could get them to provide that material as well since it was released digitally, although I assume that would apply to the print materials only, not the audio stuff.
In general I'd be happy to see more of those little extra inserts (artbooks, posters) also get released on FAKKU. But realistically I don't expect material that isn't even released digitally in Japan to get shared for publication here. For all I know the publishers don't even have the rights to release them digitally.