Changelog for update 3.5.0.26 (A) (added 22 March 2017):

- Added support for Cloud Saves in GOG Galaxy 1.2 and newer

Yeah, cloud save support added.

Witcher 2 patch 3.5.0.26 GOG wo windet man das Bitte?

Unfortunately GOG doesn't offer a patch, but only the complete installer for download. You'll have to download the complete game and run the installer again. Not sure if GOG's client called Galaxy is able to patch the game. It could be worth a try if you have issues with the download size. I don't use Galaxy, so I don't know. Maybe it also downloads everything for patching.

Changelog for Update (added 25 May 2018):

- fix for compatibility with Ubuntu 18.04
- GOG installer updates