Cavalary: Edit: Oh, yeah, in terms of game pages, do think that GOG handles those. I don't see them writing anything on their own, it's still the same description found elsewhere, sent by the dev, but do think that they're the ones who upload it.
Hardly seems like something that'd delay the addition of a title for long though. I mean, it usually won't be added on a weekend or (Polish) holiday and they tend to have a certain time for launches, not at any hour of the day (with the odd exception), but unless there's a specific reason to hold off on a launch, don't see GOG receiving a DLC from a dev and saying oh, wait, we'll just throw that in that pile and add it a month from now because we can't be bothered to copy the description to the gamepage.
Not that it's impossible, but hardly seems likely.
Hey, it is GOG we are talking about. Doing things far too slow is basically their business model ;) Also we had a big sale just recently so that could explain delays I would say.
Edit: Already got my first answer from the devs I just contacted:
"The store page parts are handled by gog, which means, that for example showing that a dlc is available in the store page, needs to be handled by gog
but uploading and setting up a dlc depends on the devs
So anything website related is GOG [they need to be contacted]
the rest of the backend is fully accessed by the publisher/dev"
