Is it still possible to find these items? I am trying for a few years now, and I´m a little desperate now,so I was wondering if you still can get the achievement?

You certainly can! I got the Sad TP last year and had started to wonder if I'd ever get the Sad Egg but I got it right at the start of this year's Morostide celebrations. Just keep going, you'll get them eventually :)

This is my first Morostide and I got both this year! Actually I find myself having more luck with sad eggs/ sad TPs when I randomly egg/ TP new people instead of just sticking to one user... though this may just be luck :P

Yep, you can definitely still get the achievements--I haven't gotten the Sad TP yet, but I got the Sad Egg achievement last week. Good luck! :)

Thank you for your answers:) I will keep going:D