Hm, this snippet does not seem to explain much.

"GoG only offers the English version anyway" this for example is not true in general. GOG offers games sometimes English only, but sometimes also with other languages. It might only be valid for Nordic Games on GOG or even not for them.

What remains is that nobody knows why languages are missing for GOG games. As you said, it could be they cannot do it or they don't want to do it.

Actually I hope it is the first case. I would rather not like to think of GOG as a bunch of lazy guys.

Chances are they're not recompiling the game's source code, but rather just repackaging it and changing the aggregation of files in the installer, along with a .ini file or similar. More likely than not though regardless of the technical issues, it is probably more of a matter of GOG having more work piling up that can and needs to be done than people lined up to do it, so some things end up waiting longer while urgent matters, then high priority matters get taken care of. That's my best guestimate as to why things sometimes seem to take forever to happen, they just keep getting pushed off for later as new high priority tasks and urgent fires need to be put out. Also, it's possible they don't have a good reminder system in place to tell people "You need to do this, this and this for game X, Y, and Z, remember?"

Now, I wonder what ever happened to the new Postal 2 expansion pack that Running With Scissors created for the game which they promised to release here on GOG... I wonder if they dropped the ball on that one and never sent it to GOG, or if they changed their minds, or if they simply forgot and slacked off, or if they did send it and it's on someone's desk at GOG near the bottom of their INBOX... hard to say. Promises are cheap in the gaming world it seems, but sometimes they don't get kept for one reason or another, whether innocent or self-serving or otherwise as the individual cases may be.

Good idea to reach out and make contact to the right people in a friendly and civil manner though and see if things can be moved along for a given issue first, and with some patience. Only if nothing happens should one resort to assembling an Internet lynch mob. :)

Last post from them on that matter:
https://www.gog.com/forum/postal_series/postal_2_paradise_lost_expansion_is_planned_for_gog/post42

Bummer. Seems like they've got too much work, too few engineers, tight time and perhaps tight finances if I read between the lines. All we can do is wait I guess. I wont be buying it on Steam then seeing it show up here later though.

Thanks, its good to know.

I will hold on to my disks to be sure. Sometimes it is possible to "trick" a GoG game into German by copying soundfiles. It worked with AquaNox 2 when I tired it a few years ago, copying the steam sound-packagefile into the GoG installation.

Maybe "compiling" was the wrong word to use. What I meant was collecting data, adding fixes and pack it into a GoG installer.

Compiling is quite correct though.
https://en.wiktionary.org/wiki/compile

Dozens of files of source code get compiled into a single executable binary just as a number of disparate files get compiled into a set of files that's intended as a complete usable package (the meaning being discussed here), and songs from different albums/artists get compiled into a compilation album.