Thanks.

1. You could've copy pasted that here. It's much easier to read than a screenshot and people can also search for it.
2. That text is to convince somebody who knows how federation could be useful to the platform, but it doesn't answer my original questions:

• what exactly should be federated?
• which problems could be faced?
• how could they be resolved?

I don't know much about fan-fiction, but I imagine it works like this:

• there are members of the platform
• every member can publish their own text
• every member can rate another text and leave comments behind

Do publications have to go into a certain communities? If so, that would translate very well to communities on lemmy. Otherwise it would be more of a blog-like thing.

Regardless of how they are published, how would content from other servers show up on the fan fiction server? This post for example, how would that show up on the fan fiction server? If it shouldn't how would it be filtered out and does the Activity Pub thing allow for some kind filtering?

Then we get to ratings: lemmy has upvotes and downvotes, mastodon has... stars? How would that translate to fan fiction ratings? Can servers change their rating systems? 1-5, 1-10, 1-100? How would you solve that?

A fan fiction server shouldn't all of a sudden start seeing posts from !politics or from pixelfed, I imagine. Then it wouldn't be fan fiction anymore.

You have to come up with a fleshed out suggestion. I don't believe you need to understand every technical detail, but you need to conceptually try and understand the different platforms and think what it would mean for them to communicate with each other. With that, you will have a point of discussion for the developers of the fan fiction server's software.