Unforntuanely, due to our somewhat constant lack of manpower, we're inhibited from providing support for game chapters but for the current, Hellbound by the time of this writing.
Here you'll find our last build for Interlude, both a server and a datapack:
http://l2jdp.com/nightly/index.php?dir= ... terlude%2F
If any given feature gets implemented after a chapter outdates, your only hope is to read revision logs so you can determine which files were missing, changed and added, engaging yourself in a "backport" process that could imply both core and datapack changes. Subversion can be a great tool for this, but depending on the features you plan to port back and their complexity, your mileage may vary.
There could be community members whose needs made them to undertake such endeavours, but it is up to them to provide support or share code changes...
Good luck.