For the Wikisources Special:UnconnectedPages does not give suitable granular information to get ready use of the pages. There is a requirement for ready local filtering. Looking at https://en.wikisource.org/wiki/Special:UnconnectedPages you can see that all subpages of works end up in a long list.

• Ability to filter out subpages

For fiction works, it is unlikely that we would individually list chapters of a work, especially due to their naming of

1. (title)/Chapter 1
2. (title)/Chapter 2 ...
3. (title)/Chapter n

So one cannot see the woods for the trees of easily identifying that a work (title) has not been added, as 40 chapters inundate the root page of a work.

• Complication of fiction vs non-fiction works.

As Wikisource replicates published works which themselves may be compilations, or have components of a work that are significant/notable in their own Wikidata sense, the subpages of non-fiction works can have their wikidata items, eg. works that are biographical dictionaries, or works that have a series of lectures. So it is not a hard rule of subpages should not show, but ability to filter. It would nice to be able to show the subpages that need items based on the parent work, however, that may be better undertaken by queries using other tools. [Would like to discuss that with someone who can help!]

• Namespaces that are being collected

For the case of English Wikisource, in the general listing of UnconnectedPages I am seeing Page: namespace pages. In the Mediawiki sense these come through appropriately as content namespaces pages as they are the content upon which we work. That said they should not be seen in unconnected pages as their content is put into the main namespace by means of transclusion, and should not be linked as items in WD, ie. a specific page of a work/ content lacks notability and would not be linked from WD.