Since there was some basis from 2012 and 2014 in your spouse's Traditional IRA, that amount does need to be entered as well as the total value of all Traditional IRA accounts. Including that prior basis will reduce the taxable amount of your spouse's Traditional to Roth conversion.
For your question about there not being any difference when you enter 2023 and 2024, or just 2024 -- if you are referring to the follow-up question after you have entered your Form 1099-R which includes your 2023 and 2024 contributions, plus the small amount of earnings, then this is what is happening. When you take a distribution from a Traditional IRA that is 100% non-deductible contributions plus some earnings, then no matter what amount is distributed only the earnings will be taxable. The non-earnings amount being distributed has already been taxed (before you put it in the Traditional IRA) whether you convert it to a Roth IRA or just keep the money.
@afromca
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