It is permanent!
Unfortunately, it is not going to help your cause whether the judgment is paid off or if it continues to remain unpaid! And I don't quite understand why an Unlawful Detainer judgment should appear on a credit record, but that is now a moot point as it is no longer appears on your credit reports.
As to why the records pertaining to the eviction and the subsequent judgment are still visible at the court house, well, they are now part of the permanent public records and there they shall remain till time indefinite. So, not much point in worrying about it.
The court house records permanence notwithstanding, there is also another avenue by which the judgment, not the evidence of the eviction per se, can be viewed is at your County's Recorder Office where all manner of documents are recorded; such as deeds, conveyances, marriage, death, etc. Another type of document that is also routinely recorded with the County is an Abstract of Judgment which is filed by the prevailing party to a lawsuit, otherwise known as the Judgment Creditor.
And the characteristics of an Abstract of Judgment is just like the court records; which is PERMANENT, even if the judgment is later satisfied, which will yield nothing but a consolation recording titled RELEASE. So, you can settle the debt with the ex landlord and receive a release, but the entry evidence of the abstract of judgment will linger on forever. That said, it is not a mandatory action and so not all judgment creditors record the abstracts, so you may want to check the records to see whether there is one recorded against you.
Last but not least, judgments last for 10 years, renewable at the choosing of the creditor for another 10 years.
fredrikklaw