I've been through the pictures and tried re-creating your workflow here... still a little confused in places... so I have some questions and hopefully these can offer some help...
1. Why do you strip silence the audio region and not simply use the detect transients feature in the Sample Editor?
2. When converting region to sampler instrument why do you choose 'transients'?
In fact, could you choose 'Regions'?
You know in the Sample Editor where you can detect and create transients... well, in the Arrange area right-click on the audio region and here you can choose to slice a region at the transient markers. This might then be easier for you?
... it depends on what you are trying to achieve.
3. Have you tried saving the sampler instrument to User/Library/App Support/Logic/Sampler Instruments/
4. Have you tried opening the Instrument Editor in the EXS24 an choosing to Export the sampler instrument and sample files? This way you can save them easily to the global EXS24 location.
5. Ultrabeat finds the files fine for me in 32-bit mode... I notice in your picture that each voice/zone is called 'Voice xx'.. mine shows up with the file name created when converting to a sampler instrument.
6. Ultrabeat is more suited to importing a kit... with 24 voices (zones)....
7. You can find the audio files for your converted to sampler instrument in your project's audio folder. (Make sure you have 'Include assets' checked in the save dialog window).
Hope this helps somewhat. Let me know how you get on.