- This registry redirection occurs only in Office Click-to-Run editions.
- If the add-in is the only entity that writes and reads the custom registry entry that it creates, there's no issue because the necessary registry redirection will occur in both directions (writing/reading).
Create a logon script
This workaround takes less development time and there will be no code change in existing products. However, you may have to run the script every day because it's not tightly integrated with the products.
Create an external process
You can create custom registry entries anywhere. However, you may have to change the code in existing products.