The PressAndHold plists are now (Ventura) in /System/Library/Input Methods/PressAndHold.app/Contents/PlugIns/PAH_Extension.appex/Contents/Resources/

Long ago (with help from here), I managed to get PressAndHold functionality added to Unicode Hex Input and called it UHI+. It almost looks like it is still using the old version. However, I looked for a file containing the string "à á â ä æ ã å ã ā" in /System, /Library, and /Users (including my custom input method) and didn't find it!

Is there a way to make an input method to use the file in /Library instead of the one in /System?

Update: There is one in /System, and it is the one being used. My grep -l did not find it because it is now binary format. But it is not in the same path as in previous O.S. versions. Now in /System/Library/TextInput/TextInput_en.bundle/Versions/A/Resources/Keyboard-en.plist which is read-only. I've edited the question due to this.

Note: There are hundreds of questions relating to PressAndHold,  Because of this (and because they're all for previous O.S. versions), I chose to write a new one rather than piggy-back on an old one which no longer applies (since Apple keeps changing the path and format).