Though the manufacturer (Pioneer) says it supports playlists, it has never worked - even with 4Gb sticks with 100 songs or less. I'm better off simply dragging the files onto the stick and use separate folders for playlists. Of course, the downside to that is the files will play in alphabetical order.
My experience with some Pioneer car players is that they play in an unusual order: By inverse date added. So newest files play first. If you're sure about alphabetical, that's much better... much easier to get around.
Is there a way to use the playlist feature in MC19 to convert Flac to MP3, then export them to the USB stick into separate folders for each playlist while renaming them so that they'll play in the order I chose when creating the playlist?
The handheld sync system can't do advanced renaming like you're describing. It can convert and copy, but it can't do extensive renaming. You would have to do something like, making converted copies to store. Then renaming them using the Rename, Move, and Copy tool.
I just played around with one playlist and used this rule for the filename:
padnumber(customdata(#),3)_[name]
That gave me a 3 digit number as the first part of the file name, corresponding to the list order. So, what you want is possible, but it's several steps. I did all of my testing with MC21. I've never used MC19, but I'd expect it to be very similar.
Brian.