Your reward sequence looks GREAT! Keep it up and pay attention to the words that have developed over time so you can intentionally be consistent with them.
When practicing inside in scenarios like this that are easy for Spring and you know, with certainty, that she will succeed, practice delaying the cookie just a second or two. You will need to increase the verbal party going on when you do this so be ready to sing her praises. Arrive, praise lavishly while you pick up the truffle and put it in one pocket and get her reward out of the other pocket. You can vary this a bit if you want to use a bag or container. Be swift about it though. The idea is to start creating a little duration (and hopefully a little impatient persistence) for waiting for her cookies as well as building up her resistance to frustration while waiting on you at a dig site. Have fun with it and, if she gets pushy about getting her reward (if you are ok with that), laugh with her and “hurry up”!
Only do this inside with searches that you know she will be a GENIUS with and only do it every few finds. For more difficult scenarios, continue to reward rapidly right there at the target.
For “blind” hides without a helper, you can also stand at the perimeter of your search area and throw the targets. I do this a lot! Throw them without really paying attention to where they land, let them cook and come back later with my dog.