WhatsApp Read Receipt How can I only partially disable read receipts on WhatsApp?
(ie. I should be able to see when others read my messages, but not have others know when I read theirs)

I have tried the script on https://forum.xda-developers.com/android/development/script-disable-whatsapp-read-receipts-t2933467, but there is no effect.
(Both parties can see when a message has been read)

The device in question has root access.
You are asking something impossible here (at least at my knowledge).

If you disable Read receipt or  Last seen, you won't be able to see other Receipt or Last seen.  

Staying incognito while being able to see other activities is not possible using WhatsApp​. You'll need a clone WhatsApp​ to be able to do that, may be.