Looking back, I should have forced property taxes
Not sure what you mean by that statement, but I use UltraTax and reviewed a few returns with similar situations.
In an identical situation where RE taxes and income taxes on the 2018 tax return were each over $10,000 UltraTax lists the refund on the 2019 Tax Refund Worksheet as "2018 st/loc refund with no tax benefit derived due to Sch A limit". It is not taxable.
In a similar situation but where RE taxes do not exceed $10,000 but income taxes make up the difference, UltraTax lists the refund on the 2019 Tax Refund Worksheet as taxable to the extent it was used to hit $10,000. Looking at this particular tax return, they had RE tax of $8,500, income tax deduction of $15,000, and a state tax refund of $3,500. Only $1,500 of the refund is taxable.
Now I see that if we would've elected to deduct sales tax instead, they still would've been at the $10,000 limit and would have no taxable refund in 2019. I guess we'll be looking at tax returns with these conditions to see if an amended 2018 return makes sense.