Is this a faithful adaptation or an alternative/expanded version?

Lansboen said:
They're 2 new stories made in collaboration with Hiroe and written by Urobuchi.

BustedBayou said:

Do they further develop important characters, Roanapur or is it just like a stand alone adventure? thanks for answering, though no one would lol

Lansboen said:

They sorta develop some side characters more, you get to know some details such as why Yolanda (the old nun) is in Roanapur. They're interesting to read but sadly the 2nd one hasn't been fully translated (yet) it's also the first time it was mentioned that Revy did SM shows which was then later also written into the main story. I guess you could also see it as a stand alone adventure though. It's worth a read for sure! And yea, I was going through all the links and I suddenly saw your question so I figured I should answer it since noone else probanly ever saw it haha.

BustedBayou said:

Black Lagoon has become so niche it's sad. I remember when I heard about it all the time in the late 2000's and early 2010's. It ended up resting somewhere in between cult anime and mainstream anime, in the dead zone of this community.

I think even if people see the show they will just move on and won't even notice there is a light novel. This are not suitable times for Black Lagoon popularity-wise. Before, it was just about a show being good and it didn't need to follow any trend nor be an event in social media... so yeah, probably no one else would have answered.

Lansboen said:

It's still very much popular... in Japan. Best selling manga in its respective magazine (sunday gx) with 2 recent spin-offs which are still running (Sawyer's already has like 6 volumes and Eda's has 1). I think that the main issue is that the light novels aren't written by Hiroe so people don't realise it's technically part of the story. Coupled with the fact that there is no official translation and you get this... In recent years it has been featured in games such as pubg mobile and even Taimanin (lol) and it's still getting a lot of merchandise. It's just that the western consumer is left out due to slow translations and irregular updates. For example, it took VIZ 1 year to translate volume 12 after its original release in Japan. I'm sure that if they'd ever announce a new anime season it would suddenly light up the community again and create a lot of buzz due to its unique setting. 

Black Lagoon is in that awkward place where most of its fanbase is being replaced by newer gen viewers who have been too spoiled by the new age of easily available content. Let's not forget that Black Lagoon celebrated it 20th anniversary already. Reminds me of a guy on reddit wondering why there was no translation of the newest chapter a week after release as with all other manga. I was like "bro, give it a month or so and maybe someone will find some time to make one"

BustedBayou said:

Everything you said is true. I just think it not being super experimental or serious like Lain, or your average isekai/shounen keeps it under the radar. i say it because there is some old stuff, irregular or finished that still gets talked about a lot in the western community. Of course, there are video essays on youtube and some hardcore fans, but it's not a matter of discussion nor a common recommendation.

Lansboen said:
I feel like a good comparison would be something like Hellsing (Ultimate). A lot of people saw it, a lot of people know about it, but there isn't really much left to talk about or it caters to a specific niche in the anime community. If you look at what's being aired these, it would feel out of place between all the isekai and moe moe blob girls from the current generation while black lagoon features older women who aren't poor weak girls going all "please save me". It's also hard to recommend something if nobody makes a show that's even comparable to it in anyway. Unironically, thanks to something as random as Akiba Maid War, people have been able to be like "hey, this kinda reminds me of black lagoon" but for the rest, can you name an anime from the past few years that would be comparable to black lagoon?

BustedBayou said:
It could be recommended stand alone. Back in the day not everything was recomended just for being similar to X. But I get it, I know it makes sense, I just don't like it. Also, I still think there's a point in which a show can be neither cult-like nor mainstreamy content-wise and that kills the buzz for it. Doesn't matter how similar other things are when something gets praised into heaven like all anime with a cult following (even if few people have really seen it). Black Lagoon is just neither, it's forgotten in the west. And yeah, 4chan is not representative, it's full of the 30-40 year olds who saw it at it's time (and still are commenting from theirs mothers basement).