Thanks for sharing those links Martin, I'm sure that they will be useful to many people.
A couple of years ago I created a Wiki page to consolidate lists of DTP resources https://wiki.scribus.net/canvas/Useful_Free_Resources
but I have no idea how useful it has been. (Click statistics - if they exist - don't say whether people are actually using the linked resources.) There are also other lists in the wiki but they're "hidden" under different page names.
I think this sort of thing should have a more prominent position somewhere but I don't know how that could be done best. Searching the different forums can be awkward and a wiki really isn't the best place for it.
I could say that a standalone website - not just for Scribus but for general DTP use - might be one way to do it but that would take a lot of work and would probably be a thankless task. (Not something I'm prepared to get into.)
Maybe just sharing links from/to various lists will be enough for most people.
Anyway, if people want to add to this list then I'm sure others will appreciate it.