Seeing as Bukkit provides backwards support for older plugins it's definitely compatible and will run, that's the whole point of the plugin API. Whether or not all features will work without any issues I don't know though but 1.14 isn't nearly as big of an update as 1.13 was and some minor issues that turned up when using 1.14 have already been fixed so I would assume that it's at least as stable as 1.14 itself (which doesn't mean much seeing as how broken the new version is I guess) And as always: If you see any issue simply report them ;) I can't really test all possible server setups myself.