The device you're using is irrelevant. If you downgrade back to Jarvis some things like libraries will revert to previous state because you resume using the older DB files that are still kicking around in the filesystem, but you now have a hybrid Jarvis/Krypton guisettings.xml file and some of the add-ons installed will have been updated to Krypton-specific versions that either won't work or might not play nice with Jarvis. I'd advocate copying the library DB files and thumbs somewhere safe then starting over with a clean Kodi configuration before moving sources.xml and DB/thumbs back.
Next time make a backup before you start, then reverting cleanly to Jarvis or a previous state is trivial.