yes, you would need to use "End Early" to end the listings from within your Auctiva account, and you can use the information on the Active Listings page currently to see when you posted the items, just noting that the end date has the correct day and month based on when you posted and the year shows 100 years in the future.
Once the data is resolved to show GTC, which is the expected behavior, you would not be able to see the post day on the active listings page and, unfortunately, you would need to review the saved listings page or your account notifications to have a count of when these listings will be renewing on eBay. Both the Saved Listings page and the notifications area have the post dates of your listings.
We do expect to have the change to our lister page very soon so that only GTC will be available for fixed price listings. This will then have the listings on the Active Listings page just show the GTC duration.