You cannot simply download the patch alone. You need the correct base.
A: Yes! Despite the name, the "AE" version of UCKP is fully backwards compatible with the 1.5.97 executable.
Community members created a specific Creation Kit Downgrade Patcher to force the editor back to a version compatible with 1.5.97.
Once your 1.5.97 Creation Kit is patched and configured, follow these best practices to ensure your mods are clean and functional:
: When you first launch the patched CK, it may ask to unpack scripts; you should accept this to ensure all game assets are accessible for editing. Creation Kit Downgrade Patcher - Nexus Mods