Is it normal that posts from other instances aren't synchronising to my home instance? I know that federation can be slow, but it's been several days since I subscribed to the instance and still nothing is showing up. The same has happened with other communities as well.
On my instance:
On their instance:
My understanding is, a community doesn't start federating until someone on your instance kicks it into motion, usually by searching for it (as you have just done). From that point onwards, posts from that community are shared with your instance, but it doesn't go backwards in time.
This is my impression, but hopefully someone else will chime in.