If you are being asked to enter the FMV for your Traditional IRAs, you would enter the total FMV for all Traditional IRAs even if you did not have a 5498 for all accounts.
If you never had any non-deductible contributions to any of your Traditional IRAs, but you are still being asked to provide the total FMV of those accounts, the number you enter will not affect the tax calculation or be reported on Form 8606.
Turbotax has a box to enter the FMV of my traditional IRA assets, but it is not presenting a similar box for my wife on our joint return. How would the FMV of her IRA account be captured in Turbotax?
You would have to to indicate that any excess contributions from a prior year was credited to the current year and the box will appear as shown.
When you go through the input screens, there would be a box to enter the excess amounts from prior year then excess amount withdrawn, you would hit no, then to the next screen how much excess to the current year, next screen hit no, and then to the screen of Tell Us the Value of All Your Traditional IRA accounts from 5498.