These sphinx ports are not hard dependencies of anything else in the collection. It seems like their only purpose is to build documentation, when the upstream project does not ship pre-compiled man-pages.
Recommendation: mark unmaintained
denyhost, dia, the hfs utils, and leveldb are getting only minimal attention (if any) from their upstream developers.
streamlink seems more active, and hence a good candidate for adoption (along with its python3 dependencies) if anyone is interested.
firefox and midori are unwieldy to build from source. Adopting either of them would almost require a dedicated build farm, either to keep up with the cadence of its releases (firefox) or its electron dependency (midori).
librsvg-compat is still mentioned in /etc/prt-get.aliases as a viable substitute for librsvg, but it has not received back-ported bugfixes for several years now. Its dependency libcroco is not needed by anything else in the collection.
Recommendation: drop, or move to contrib.