There are other once-blooming climbing roses from China, which are rather hard to classify. People kept confusing this rose with Lijiang Rd, another once-bloomer large climber, which clearly has gigantea heritage. This rose shows no trace of gigantea and is much more china-like in every feature, including the green color of the new growth and the shape of the receptacle, sepals and blossoms. .

While the lines between horticultural classes and botanical taxa have been pretty well blurred in roses, it seems to me that a China rose as a member of the traditionally understood class (cultivar Group) assignment should simply not possess once-flowering behavior.

As for the supposedly "wild form" of Rosa × chinensis, it has not been scientifically demonstrated that those wild populations are actually conspecific with Rosa × chinensis, whose type was a cultivated crimson China belonging to a group that DNA evidence suggests are really hybrids. It's pretty clear from the relevant studies produced so far that the taxon being called R. chinensis var. spontanea is a progenitor species of R. × chinensis, but it is not the sole progenitor species. The assignment of such wild forms to R. × chinensis without DNA evidence at a time when it should have been possible to perform the needed studies was pretty clearly influenced by a strong confirmation bias, but it has not been supported by molecular evidence. It isn't rational to recircumscribe a species that was based on a cultivated type of unclear origins and that could be a hybrid to include a wild taxon, and it makes just as little sense to broaden the circumscription of a well-established cultivar Group (class) to incorporate features of that wild taxon without clear scientific evidence.

For one study that examines the genetic relationship between a cultivated member of R. × chinensis and "R. chinensis var. spontanea," see: www.researchgate.net/publication/236941747_Untangling_the_hybrid_origin_of_the_Chinese_tea_roses_Evidence_from_DNA_sequences_of_single-copy_nuclear_and_chloroplast_genes

From my perspective, the assignment of that apparently wild taxon to Rosa × chinensis was on par with the recognition by some of Rosa gigantea as a variety of its own hybrid, Rosa × odorata. Like Rosa × odorata, it appears that Rosa × chinensis should be regarded as a hybrid. Assignment of a progenitor species to its own hybrid is paradoxical.

To me, a "once-blooming China" is something of a contradiction in terms.