Does a sponsor in a Chinese visa application have to do anything upfront?

We are currently attempting to get a Chinese visa (about the 6th one I have held in the past few years, but the first one I am applying for while using the China Visa Service Center's online form).

In said online form, item 6.5 asks for a "domestic/foreign sponsor". (Previous visa application forms I used did not yet contain that item.) We're paying for the trip ourselves, and the online form had the option of marking item 6.5 as "not applicable". We ticked that box, as neither our Chinese inviter (who is probably less capable of paying for such a trip than we are), nor the spouse of the applicant (as was suggested on this guide) made sense to us. Furthermore, I found this recent forum thread (albeit from a different country than mine) that implied specifying a sponsor is not necessary on the current Chinese visa application.

Now, the visa service center is contacting us and telling us the form is incomplete because we have not provided any information about our sponsor. If we do put our Chinese inviter there, do they have to do anything, such as declare towards their local authorities their readiness to cover our expenses, should this become necessary? (And do they have to somehow prove their financial capability of sponsoring our trips?)