I looked each port for the specific Sphinx's version it requires.
Remaining ports:
audio/ncmpc/Makefile:MANPAGES_BUILD_DEPENDS= ${PY_SPHINX} audio/aubio/Makefile:DOCS_BUILD_DEPENDS= ${PY_SPHINX} audio/musicpc/Makefile:DOCS_BUILD_DEPENDS= ${PY_SPHINX} graphics/zathura/Makefile:BUILD_DEPENDS= ${PY_SPHINX} \ security/libscep/Makefile: ${PY_SPHINX} lang/pocl/Makefile:DOCS_BUILD_DEPENDS= ${PY_SPHINX} devel/gearmand/Makefile:BUILD_DEPENDS= ${PY_SPHINX} devel/gearmand-devel/Makefile: ${PY_SPHINX} sysutils/zrepl/Makefile:MANPAGES_BUILD_DEPENDS= ${PY_SPHINX} net/savvycan/Makefile:BUILD_DEPENDS= ${PY_SPHINX} net/frr7/Makefile:MANPAGES_BUILD_DEPENDS= ${PY_SPHINX}