The answer I currently have, is that this is the plan, but I'm not sure how fast it can be done.

Here's the gist: Nightdive reached out a few weeks prior to release and we made a deal for the use of subtitles. We offered our subtitles English, French and Spanish, made by the ScummVM team and members of the ScummVM community for use in the Enhanced Edition, and they offered subtitles for the remaining two languges (Italian and German). And to credit us properly -- which is unfortunately currently not true and will be fixed in an upcoming patch.

Our subtitles are made by first transcribing the audio from the official localized releases. So the English one matches the English audio, the French matches the French one and the Spanish matches the Spanish one. This is kind of important to clarify because the localized audio for French, Italian, German, Spanish (FIGS) may differ at a few parts from the English one, and furthermore sentences in a dialogue may be broken or merged differently. It also means that if we ever support (and I aim to at some point) mixing subtitle languages with different audio language in the original game, then extra work would be required to at least address any such special cases than can be practically addressed.

Now, we do have the Italian and German subtiltes courtesy of Nightdive since yesterday, but at a quick glance it seems (to me) that they be translations of the English subtitles. This means that they would work if used with the English audio version, but they will be inconsistent (at least in a few places) with the Italian and the German audio. Some additional editing is also required.

So I think the current plan is to merge them in a bundle soon-ish, and then somehow inform the community members to playtest and report issues so that we can optimize them. Personally, I don't speak Italian, and my German are very basic so I can't help much other than resolving technical issues and updating according to feedback.

Are the videos subtitled in the new version?

The videos are not subtitled in the Enhanced Edition as of yet - the audio is also still only English in that version.

Maybe a future update will fix this, since the subtitles do exist for those cutscenes, as can be seen in the classic version when using the subtitles SUBTITLES.MIX file from the ScummVM website.

Thanks a lot for the explanation. Once the playtesting starts, where should I report issues (assuming I find any)?

I would prefer issues to be reported on the ScummVM bug tracker as a new ticket here:
https://bugs.scummvm.org

How to report a bug: https://docs.scummvm.org/en/latest/help/report_bugs.html

But if this proves difficult (it requires creating a github account (if you don't have one) as a first step) you can reach out on the ScummVM discord or forums:
Discord: https://discord.com/invite/4cDsMNtcpG
Forums: https://forums.scummvm.org

You can also post here on GOG forums on a new thread, but keep in mind that I'm more likely to notice and track issues reported via the bug tracker ticket method.

Note: this concerns only issues with the subtitles (and the gameplay) of the classic version that is powered by ScummVM. I am clarifying this just in case people get confused.

A minor correction and a minor update.

Correction: The subtitles for Italian and German from NightDive studio seem to be proper transcripts rather than translation from English (except for maybe one place which can be easily fixed). Again this is an estimation on my part, assisted by others who observed the same, but like I said, I don't speak fluently either of these languages. Hopefully, though, we are not mistaken :)

Update: I've now actively started integrating the subtitles for the Italian version, doing some quick testing in parallel. I don't have an estimate of when this is going to be completed, but it looks to be quite easy so far, and fingers crossed, it will go smoothly for the rest of it. German is next. We will probably upload the updated version on the ScummVM website once this process is complete. The new subtitles file will include a few improvements for the English, French and Spanish translations that were made between 2020 (when the last version was released) and now.

On Steam, the Enhanced Edition of the game now also comes with the original classic version powerd by ScummVM. The current difference there is that on Steam a much newer version of ScummVM is used, ie. ScummVM 2.5.1 which is a good thing! The other difference is that since a few hours ago the Steam version included the subtitles file for the original version (currently only English, French and Spanish) so people won't need to get it from the ScummVM web site.

I think this means that it's very likely the GOG version will offer these updates as well (the newer ScummVM version, and the included subtitles), and hopefully they'll keep the ScummVM version and the subtitles up to date when we release new versions.

That's great! Good news after good news. Heck, I might be tempted to buy the Enhanced Edition, just to thank them for the transcription. XD

I do use 2.5.1 already, but it would be nice to see that version become the default for games on GOG (although I understand not wanting to test new updates, then repackage things for Galaxy and the offline installers, if you have a working setup already).

Quick update, I've now integrated the German and Italian subtitles from Nightdive Studios on our Excel with the transcripts, and produced a new SUBTITLES.MIX file for internal testing (which will probably not take long in my opinion).

After that, we will probably upload the final revision on the ScummVM site and await for your feedback to improve it!

The new subtitles file will work best with a ScummVM version of 2.6 (currently on release candidate status) or greater.

Should we expect issues using 2.5.1? I mean, I am willing to install 2.6 even if it's not the stable version yet, but I'd like to know if it's necessary or just recommended.

Not many. The most prominent is that I fixed a regression where special characters like some quotation marks, ellipsis, (TM) glyph would not show up in the game, and the new and updated subtitles make use of those. There is one additional fix that refers to the German subtitles with the German audio language, which is addressed in 2.6.0 (or greater).

And, ideally, I would like anyone who will be actively testing and reporting back for corrections and improvements to be on a version that includes those fixes.

But, it is indeed only a recommendation, not a requirement.

The new version (version 7) of the subtitles for the Classic version of the game is now up and available from the ScummVM site.
https://www.scummvm.org/games/#addons-bladerunner

As written above, this new version includes the Italian and German subtitles courtesy of Nightdive Studios, with minor edits (...).
It also has many improvements to the French transcript, which Kwama57 has worked tirelessly on during the last week.
And a few fixes to the English and Spanish transcript which were done since the last release of version 6 back in 2020.

The full credits for this release are as follows -- also included in the bundled readme.txt file:
English subtitles arranged by Athanasios Antoniou (Praetorian) & Thomas Fach-Pedersen (madmoose)
French subtitles arranged by Xavier Mohedano (Kwama57)
Spanish subtitles arranged by Sergio Carmona & Víctor González Fraile
German and Italian subtitles courtesy of Nightdive Studio

The subtitles should work with any ScummVM version starting from 2.1.0 and greater.
Testing with a release candidate daily build of ScummVM 2.6.0 or a 2.7.0git (development build) is highly recommended.
When ScummVM 2.6.0 is properly released (soon-ish), it's probably for the best to use that to run Blade Runner classic version anyway.

As always, let us know of any errors that you've spotted, comments, and suggestions for improvements.