Your comments about problems with audiobook playback order seem to relate to ID3 tagging problems using BOOK MODE.
Filename ordering problems (and FAT table sequencing) applies only to FOLDER MODE.
Maybe it is hard to provide best advice without seeing examples of your ID3 tags??
Maybe you could post here one example of your data entries for all the ID3 fields in one of your audiobook files?
I have never tried using 5-digit dates in the audio title field of my ID3 tags. I typically use 2-digit prefixes (followed by a space or a hyphen) then text labels of 8 or more letters in the audio title field. The first 8 letters of the text labels should readily indicate the specific title of the audio file (not the artist name, etc). Seems like you have proven that 2-digit track numbers do not solve your situation. Maybe you can try using helpful data in the Album Title field in your ID3 tags.
And maybe you have discovered that BOOK MODE ignores your physical layout of subfolders in your AudioBook folder. Your subfolder layout can be used to help you properly manage your files on your player.
I can tell you that it really is possible to get this all to work in BOOK MODE with the correct combination of data entries in the ID3 tags. Once you have a working set of files you will hopefully start to enjoy using this handy little audio player.
