I had an interesting minor issue with a fresh installation (not a backup restore) of MacOS Catalina 10.15.4 the other day. Everything went OK but the stock Dictionary app had all local dictionaries missing, everything except Wikipedia. Dictionaries in the red box were missing.
A quick reinstallation didn't help so had to pinpoint the location of these files and investigate further. Well, the previous MacOS's have Dictionary files stored in ~/Library/Dictionaries/ and user specific Dictionaries are in /System/Library/Assets/com_apple_MobileAsset_DictionaryServices
In MacOS Catalina these are in /System/Library/AssetsV2/com_apple_MobileAsset_DictionaryServices_dictionaryOSX
To get this up and running search for the AssetsV2 folder as per the above. In my case this folder was empty however it should contain something like this
If AssetsV2 is empty, like it was in my case, you will need to locate the .asset files and com_apple_MobileAsset_DictionaryServices_dictionaryOSX.xml in your backup and copy them over.
Before you copy the files over you will need to disable SIP (System Integrity Protection):
- Restart your Mac (Apple > Restart...) while holding down Command(cmd)+R keys until the Apple logo appears
- Boot into MacOS Utilities window
- From the menu Utilities>Terminal
- Enter csrutil disable
Once you copy the files over, repeat the process above to re-enable SIP by entering csrutil enable in Terminal window.
That should do the trick. Hope this was useful.