Howdy, I didn't respond initially because of the link to PowerAuras that threw me off.
This PaladinKanons add-on uses the old UNIT related buff events rather than the OBJECT related buff events the game currently uses. This means the add-on is code broken not just localization broken.
In addition to your English localization changes that you have made, you will need to change all the EVENT_UNIT_... to EVENT_OBJECT_... and adapt the code similar to how I have done in my Buff related add-ons, like DoTTimer and PlayerHUD. Meaning that all the .unitId or .units calls need to be changed to .objectId or .objects calls, and BUFF_ADDED has new passed table value of buffId instead of index so the code there also needs to be changed.