thanks +Sven Tiffe
, +Aravind Krishnaswamy
, +James Gallagher
for your tips. Sadly I normally empty my trash directly after deleting things and I did it with those photos, too, before noticing it affected my posts. So undeleting them isn't an option anymore.
But as I said in German: I'm more or less over it. Google Photos is beautiful and I use it to archive all my photos now. Undeleting would have given me chaos in there again, because my metatags on photos are off after processing them. My plan is now to completely archive the photos and share highlights from there again over the next few weeks/months together with new stuff i'm working on. also i'll make selected albums public in the end. I believe it will be better sorted than before and so i'm positively looking forward to it now. Thanks for that, Google ;)
Maybe as a feature request as it seems you guys are working on Google Photos: Editing metadata in the informations tab of the photos (or even bulk editing for a selection of photos) would be much appreciated. Currently i'm working on all photos i have in ExifTool.