CreateSpace was owned by Amazon. They recently opted to either fold it into or turn it into Kindle Direct Publishing. That per se is not an issue.
The KDP set-up process is actually a little more streamlined and easier than CreateSpace's had been. So far so good.
The format check for KDP is live. With CreateSpace, you submitted your cover and internal files for inspection and waited up to a day for the results. This is nice.
Once the inspection was passed, you could then and can now order proof copies. No changes there.
The problem is that KDP does a detailed content check after all that. That can take days. They will also reject books because of problems that occur. They count blank pages. They check page numbers. That could be a bit awkward under some circumstances. Worst of all, they check the printed book's title with what you called it at set-up. That has been causing no end of grief.
The project's title (including subtitle) is, say, The Divine Comedy (Deseret Alphabet Edition). Perfect for trying to find it on Amazon or other booksellers.
The cover has both that title and 𐐜 𐐔𐐮𐑂𐐴𐑌 𐐗𐐪𐑋𐐲𐐼𐐨. So far so good.
The title page, however, simply has 𐐜 𐐔𐐮𐑂𐐴𐑌 𐐗𐐪𐑋𐐲𐐼𐐨, and now we have a problem. I get an email back from them saying that the language of the title page and the language of the project's name do not match. (Strictly speaking, the script of the project title and the title page don't match, but we'll let that slide.) This bugs me. For me, the title page is intended to be a reproduction of the original's title page, just in a different script. Now I need to have both scripts present on the title page.
Even worse, the script of the spine and the project title don't match. Now I'm getting really annoyed, because I have to have both on the spine now, or just the Latin title and that's even worse.
Even worser worse, I haven't completed the final round of their review and therefore don't know if there is something else I'm missing, because their error report is a little on the vague side by simply saying that something is wrong then pointing you to their instructions, viz.:
Book detailsMake sure the information in your interior and cover files exactly matches the book details (e.g., title, author name, ISBN, language) you entered during title setup.
Check all locations? Headers‽‽ My headers usually have something like author name/chapter title. That won't match. In the hypothetical case we're considering, I have book title/canto number (as in Hell/Canto I). Are they going to ding me for that? Can't they just tell me where they want something different and keep me from having to double-guess?
So that's where I am with Dante. I keep adding the Latin title in more and more places and every time they say that something is wrong. I'm down to the spine. If that's not enough, I don't know what to do.
Maybe go back to Lulu.