What are you trying to enter in Extra that you want to appear in your bibliography?

The appropriate way to add the original title (or other citation fields like DOI, etc) is to write it like this in Extra:
Original title: This is the original title

Any valid CSL field can be added that way and styles that are written to use those variables will show them https://www.zotero.org/support/kb/item_types_and_fields

You need to specify the CSL variable type that you are entering as an extra, not just the value:
https://docs.citationstyles.org/en/stable/specification.html#appendix-iv-variables

For example, use original-title as the type for your original title.
Then the style must actually use that variable type. It should be the case if its guidelines say that this information must be included in citations.

This is very helpful. I did use "original-title" in the Extra field, but it did not show up in the citation. However, when I put the needed information in the URL field, it does show up.

I am using "Chicago Style 17th Edition with Note and Ibid" style.

Any thoughts?

You're right! I worked on it last night and figured it all out. I have edited my style to add all the fields I need.

Thank you for your help!

@JohnDuffy, I wasn't able to implement exactly what @bwiernik suggested due to a lack of the necessary technical knowledge. However, I found an alternative solution by creating conditional statements in my citation code to address the issue, and it worked perfectly. My book is coming out on September 2nd. I'm happy to share more details if you're interested.

What citation style are you using?

@JohnDuffy, I use Chicago 17th. This is what I did.

Using a Visual CSL Editor, I clicked on the DOI number. Then, under the "If Not (Legal Case)" section, I added a condition: if the variable contains "original-title," a prefix of "(orig. pub. as" and a suffix will be added in the affixes.

In this case, whenever the "Extra" field contains something that starts with "original-title," the content after it will be included at the end of the citation.

You can create similar conditional statements for any additional information and add them to the "Extra" field.

This process might seem a bit challenging at first, but it's quite manageable. Just be sure to refer to the Standard Variables listed in this link:

https://docs.citationstyles.org/en/stable/specification.html#appendix-iv-variables

I am happy to hop on a quick Zoom call to review how you can achieve that. If you feel comfortable sharing your email, I can send it to you at a time that is convenient for you.

Just emailed you.

I am happy I was able to help!