Currently, it is not possible for customers to choose which Jira card fields to display in Confluence Whiteboard.
Customer specifically wants to have the remaining estimate Jira field in Confluence whiteboards.

I tried to replicate the situation on my test site, i created a Jira card first with 'Time tracking" field in Jira but when i imported it as Jira card on my Confluence Whiteboard, i could see only few pre-defined fields and remaining estimate is not one of them.

It displays like below in Confluence whiteboard:

But below remaining estimate field in Jira card should also be visible:

Workaround:

If you change it from card to embed display, you can see all the details on Whiteboard.