Swapped to my alt account on feddit.de and subscribed to the community.
I can see the post and hopefully you can see this reply.
However as of 30min after this thread was created I can only see the reply from a lemmy.world user, not the others.
Maybe me subscribing to the community will help federation. But feddit.de has occasional issues in general.
Edit: the fanatics.social reply also shows now
Edit2: a few more newer ones starting to show up, so I assume federation is slowly happening?
Edit3: older comments from other instances are also starting to show up.