They’re in the process of revaluing the valor catastral, some have been done and some are yet to be done.
The valor catastral is the rateable value of a property and land it sits on and is not a reflection on any assumed market value. It’s used to calculate IBI, rubbish collection, plusvalia and non-resident taxes. It is not used for capital gains tax calculations!
I repeat it is not a assessment of the ‘offficial’ or market value of a property.
Although not used to calculate a market price, for tax purposes the valor catastral is used to calculate an official price in Andalucia (and I assume all regions) called ‘valor fiscal’. Although it does not affect the seller it can lead to higher costs for the buyer., as if they buy below this amount, they do have to pay the transfer tax/IVA on the difference.