In the US fines are not tax deductible, so that's one fiscal difference between taxes and fines. I have no idea if Spain considers fines to be tax deductible or not.
If I steal an apple from Walmart, should the fine be 1 percent of the value of the apple? Clearly not.
That case was about a $5000 a day antitrust fine, which had accumulated to $1.6 million, but had not forced compliance with the law. The Supremes concluded that the fine was not excessive, because the business was doing well enough not to comply despite the fines.
The fine would have to be grossly in excess of what it would take to force compliance by a reasonable business. A fine that amounts to a doubling of the property tax would almost certainly not be a violation of the Eighth amendment.
Relatedly, I got a ~$5k state refund last year and I'm not paying additional federal tax on it this year because the SALT deductions are now gone under Trump's tax changes, so my state tax burden doesn't affect my federal tax burden anymore.
Since you won't be deducing SALT in 2018, any state refund in 2019 wouldn't be reportable for federal tax year 2019.
If this were otherwise, people would have purposefully massively over pay to the state in 2017, claim a large deduction in tax year 2017, get a large refund in 2018, and not have to pay back the deduction they didn't really deserve.