Disabled, queer, genderqueer, raised bilingual outside the Anglophone world, has lived in "developing world" (Anglophone and non-Anglophone), mostly white. I'm also that person you think was complaining for the sake of complaining, when really I must have been bad at expressing my concerns. Putting that aside …

I got the sense from the anthology call that you all were trying to accomplish too many things at once with your call for submissions, given the time frame.

Are there lots of steampunk writers who can write from a disabled perspective? Yes.

Are there lots of steampunk writers who can write from a non-white perspective? Yes

Are there lots of steampunk writers who can write from a non-Western perspective? Probably fewer, but still significant numbers.

Are there lots of steampunk writers who can write from a non-English-speaking perspective? Probably fewer, but still significant numbers.

Are there lots of steampunk writers who can write from all of these perspectives? Probably not.

Did you want all writers/stories to represent all categories? I don't know. I read your call for submissions multiple times, and reread it when you & the publisher told me I was reading it wrong. I still think it comes across as wanting each story to represent each of the four categories, or most of them.

I don't hit all the categories, so I didn't try to write for it. I would guess that there are others who chose not to submit because they and/or their stories didn't fit all the categories. That might have affected your numbers of submissions from people w/disabilities.

In addition to the above questions, I had another question going through my mind back when I read the call:

Are there people who can write from all four of these perspectives but never considered writing steampunk? Huge numbers.

If you're looking for representation from all four of the categories, that means approaching writers who fit them and asking them if they're interested in writing steampunk. The downside of that is it inviting non-Westerners to participate in a Western literary tradition could come across as patronizing. It would need to be done carefully.

Since you asked for advice: If you're satisfied with the diversity in the anthology, publish it. If you are not satisfied with it, determine what exactly your book is missing and solicit more submissions. Do that by inviting specific writers, and/or by putting out another call for submissions. Decide what you biggest needs are in terms of diversity and content and make them clear. Also make clear if you are looking for diversity in author identities, in story content, or both.

My own opinion about representation: As for whether the authors are disabled themselves, I don't feel strongly about this as long as they portray characters realistically (given the world they've built) and tell a good story. I am disabled, but I don't have every disability that I write about in my stories. I am queer, but not in all the manifestations that arise in my stories. I am multilingual, but sometimes write from the perspectives of people who are fluent in languages I'm not really good at. I don't think it's a problem when I do it, and I don't think it's a problem when other people do it, as long as they use empathy and research.

My own opinion about whether you should publish the book: Of course you should—whether it's now or later after you so elicited more submissions. You had the same demographics at the beginning of the project as you do now. You had the same vision then as you do now. And I'm sure the writers whose work you have accepted pending publication could use the money. Regardless of demographics, we writers tend to be an underpaid bunch, and as I recall you were paying SFWA professional rates. Writers need more of those gigs.

Good luck and best wishes!