Not really. Most fediverse software create a cache of content on their own servers to make it easier to display content for their local users.
So… this brings the issue of “hosting”.
For example, if I link to this Torrent file: https://download.documentfoundation.org/libreoffice/stable/7.5.4/deb/x86_64/LibreOffice_7.5.4_Linux_x86-64_deb.tar.gz.torrent (LibreOffice 7.5.4), this link (not the file), and this entire comment, will have a copy in every instance that creates a local copy of content they receive.
(Some fediverse instance even locally host images to avoid fetching images again and again.)
Now, if we assume that a simple link is “illegal”, even if it is not piracy (like in the case of LibreOffice above), then all the instances which created a local copy of this reply might be put in trouble.
The fediverse is fast in fediblocking users and instances which tolerate activities that may place most instances into legal issues.
I saw your reply but it is yet to federate in other instances.
No. Again, you just posted a link. What determines a link as a potential Copyright infringement is the content it is linking to.
Let's use an example: https://download.documentfoundation.org/libreoffice/stable/7.5.4/deb/x86_64/LibreOffice_7.5.4_Linux_x86-64_deb_helppack_en-US.tar.gz.torrent
It's not a magnett link, but just the same, I linked to a torrent file. It is not a Copyright Infringement.
But if the link is a link to a content that violates the Copyright Law, then there is potential issue.
Linking by itself is vague. There are countries that don't consider links as Copyright infringement, because again, these are just links. Only the host is causing piracy / infringement. However, there are countries that considers linking as an act of distribution of an infringement material, so it is illegal for these countries.
If you have a script, then you can. You can submit links to web archive services and they'll scrape the site to archive a copy of it.
Oh yes, definitely. You can count on instances defederating/blocking instances tolerating Copyright infringement activities. There are various blocklists available for instances to use, and there are groups where admins share and discuss these things.
So, sooner or later, an instance tolerating Copyright infringement will find itself isolated and potentially an island.
It can remain online as a regular site. It just won't be federated with anyone.
One more thing. There are blocklists and admins who will defederate instances just because they are not blocking certain instances. Thus, if I am running my own instance, I might be forced to defederate from an offending instance to avoid being defederated by everyone else.