Ah, that explains the problem. jAlbum doesn't recognize those files as objects that could be included in an album, so if they're sitting in the image directory, or in a folder below that, they'll just be ignored.
If you open the program directory - Tools, Open directories, Program directory - go to the system subdirectory, and look at filetypes.xml, you'll see the extensions that jAlbum recognizes. You could add those other file extensions, and provide a representing icon for them (in the program's res subdirectory). I'm not sure what a skin would do with them, however.
I updated (19.x), added the lines to filetype.xml again, but this version doesn't process non-image files: No reference to the files in index, nor are the files copied. IIRC, the older version had a checkbox to enable processing of non-image files as if they were images. But I do not recall where this checkbox was...(I still use Chameleon skin)
Please verify your changes to system/filetypes.xml and your addition of that icon again. There should be no such change in jAlbum to cause what you describe. (I just added a pdf file to a project and made the album. It showed up)
I updated (19.x), added the lines to filetype.xml again, but this version doesn't process non-image files: No reference to the files in index, nor are the files copied.
I just tried the same thing with jAlbum 20.1. I added the lines to the program's system/filetypes.xml file, and added the track.png logo to the program's res folder. I then added a KMZ file to a folder and made the album. The folder is processed, and the KMZ file is sitting in the output directory (in that folder).
Works with Minimal and Chameleon. Newer skins might ignore the file, however.
ETA: Attached is what I see in Chameleon for that folder. Clicking on the icon offers to save the file, since the browser doesn't know what to do with it.