Glad to help clarify things for you.
The TTX program only uses the information from your tax bill for the sole and only purpose of determining what percentage of your "actual" purchase price, gets allocated to the land. No other purpose for the tax bill on that front.
Folks get confused because the valuations on the next tax year's tax bill may be different - sometimes by a rather large percentage too. But it doesn't matter. Your 2019 tax bill will "always" be available at the tax assessor's office until the end of civilization as we know it, should the need ever arise for you to "prove" how you arrived at the percentage you used.
