I don’t know if this will be helpful or not, but I’ll toss it out there.
I needed to build an archive for digital images. The catalog had a hair under 5000 images organized into 300+ collections. Seeing that the csv importer wouldn’t handle images, I opted to go with the built-in WordPress importer.
To get it to work, I reverse engineered an export and then wrote a little program that generated the xml necessary for the import. It handles posts, images, featured images, and tags (and the images are associated with the post via the post_parent field). My program also sorted out my photos into a folder structure that corresponds to my WordPress upload configuration. In the end, I uploaded my images (yes, that took a while), ran the import, and ultimately had my website completely populated.
So, it is possible to automate a batch population of a WordPress site. I wrote my program in Delphi (the only language I’m fluent in), and I was able to take advantage of a uniform image naming convention that made it easy to keep things organized. I don’t know how well my little program will work for others, but I think the idea is fairly simple. If you have the ability to create your csv file, it might not take you much more work to create the appropriate xml file.
You can see the end result here