In the course of making my custom vocabulary lists, I occasionally add a word that is not in the Skritter dictionary. Is there a way I can retrieve a list of the definitions I have added? As far as I can tell, Skritter uses EDICT for the Japanese-English dictionary. If so, I would like to forward my contributions to the EDICT project.

No Skritter doesn't do this automatically. But you can achieve this manually:
Prepare yourself a new list, e.g. My Items Added.
Once you have added an item in a list, go to this item, open it and click on the small little add button in the top left corner (it's either blue, if not added / learnt so far, or green, if done already). Then add this item to your newly created list.

In case, you have added several items, you can do this also in bulk. Go to the relevant section of the list and tick the items which you have added. Then select from word actions on the top of the section "copy items to" and select your new list from there.

In this case, you have this item in 2 lists, in your original list as well as in your My Items Added list. You may never learn this list, but you have an overview over what you've added.

I can also just send you an email with all 194 items you've created, if you like.