I'd like to ask if it would be possible to add the Galaxy achievements to the game, I think they would add an additional challenge and would be greatly appreciated by players.

I know the game was made with Ren'Py, and natively this feature doesn't seem to be supported on GOG, but lately some developers have managed to implement them independently anyway:
Just Deserts
Leap of Love
Slay the Princess

Perhaps it may be worth contacting one of them to find a solution or ask GOG support if they know anything about it or have additional tools, such as the Steam SDK wrapper currently in beta.
Thank you in advance!

Thanks for info.
Yes, the game is made with Ren'Py and to be honest I failed to implement achievements here.

I will contact developers of the listed games and if they are made with Ren'Py I do my best to use their experience and implement achievemetns for the GOG players!

Awesome, I really hope you can find a solution!

I also found this discussion on Ren'Py's Github if it may be helpful, the last post seems to be from the developer of Leap of Love: https://github.com/renpy/renpy/issues/4309

Just joining the discussion to say that I am also thankful @KamtiGames that you will look into this :)

Thanks for info and your support, guys. Working on it.

Hello again, you may have already known this, but a friend pointed out to me that the Galaxy Docs have the link to the solution devised by the devs of Just Deserts. It definitely wasn't there a couple of months ago.
https://docs.gog.com/sdk-game-engines/

There was a further and very promising development of the situation.
MarkoH01 analyzed the solution found by one of the aforementioned developers and seems to have found the exact procedure to follow for the achievements to work properly, all using the Steam wrapper provided by GOG, or at least a version of it.

The procedure is very simple and reproducible, so much so that I could follow it even as a non-developer, and has already succeeded in getting the achievements of at least one other developer to work.

At this link you will find the necessary files and the exact procedure: drive.google.com/file/d/1OiN9hefbuXbD-BgqRLUZX05xhqFDvNTh/view?usp=sharing

GOG itself will probably update the documentation to allow even more developers to properly use the Steam wrapper. If you have any questions let me know, but I think this is the easiest and most promising way.

Yes, I can confirm that achievements do work in the latest build. I am glad that my information helped you making them finally work and I am looking forward to get them implemented for "The Book of Bandmaids" as well. Thank you for doing this.:)

However I also have two tiny complaints:

1) The last update apparently deactivated the unrated DLC (I can install the previous version with the DLC working fine but if I start Galaxy it will detect that there was a newer build and the moment I install the last build the DLC does not work anymore).

2) For the user to use the rollback feature on GOG you should never unpublish any builds as GOG is stating themselves here:

"We kindly request that you do not unpublish any previous updates that have been published on the Master branch. This allows users to make use of the rollback feature in the GOG GALAXY client in case an update that has been published on the Master branch turns out to have been either prematurely published or exhibits major game-breaking bugs."

Because of this not being the case here I have to uninstall the game and reinstall it with the older installers and refusing the actual update to keep it uncensored and still have achievements work. So please correct the latest build with working unrated DLC and don't unpublish previous builds in the future :)

Hello KamtiGames,

first let me tell you that I really appreciate what you have done so far and how you are trying hard to get achievements to your games here on GOGers to enjoy. I can aslo confirm that the latest build has fixed the DLC issue for Conussia. Thanks for this as well.

Regarding the "Book of Bondmaids" achievements: they are probably still set to development mode which is the reason why they are invisible in Galaxy and why Galaxy does not show the correct percentage. In my instruction text I mentioned this final step as well. Take a look here:

https://docs.gog.com/sdk-stats-and-achievements/

Scroll to the sections "Achievements Modes" and take a look at the screenshot there.
You can see the buttons "Add now" "Upload VDF" and then the setting "Achievement mode". This Achievement mode need to be set to "Production" (it's marked with a red square in the screenshot). Then the achievements should be visible in the client again.

Btw: I could not find a walkthrough or anything similar for Conussia and I think I am pretty much stuck right now. I have no idea how to progress with the investigation or the story itself. I found the secret passage, created the mirror, bought all dresses and let people join me in watching the princess and nobles ... I also worked at the tavern .... how do I make progress in the game?

Hello, thank you for your work, I'm so glad you were able to add them!

As for the Book of Bondmaids achievements, probably as Marko says they are invisible, and it should be enough to follow the process he mentioned.

I also plan to complete all the Three kingdoms story: Conussia and Book of Bondmaids achievements very soon, so I will be able to provide further feedback if any problems arise.

Hello guys,

It seems achievements appeared in GOG Galaxy for The Book of Bondmaids.
Yes, it was wrong status, it's fixed when I settle it to "Production".
Thank you again. I wasn't able to do it without your help!

@MarkoH01,
please find attached guide. I hope it'll help a bit:

https://drive.google.com/file/d/1hYJ0KNsFRpb5Q17qFQWJVgYGAdbBnS0q/view?usp=sharing

If you still have question after reading it, let me know, I will help.

Glad to hear this. I am always glad to help a dev that cares about GOG and their customers and who has such passion for their game :) Thank you very much for the guide. I will take a closer look at it after work and I am looking forward to continue with the game.