Confirm what is actually on record
An unpermitted room, an open Code Enforcement case, and a recorded title matter are not the same thing. The City's case lookup shows certain active and closed cases, but warns that complaint descriptions are allegations, not necessarily confirmed violations. Its legalizing construction guidance points owners to SJPermits.org for property permits. Ask the City about an open case and your title professional about any recorded matter.
San Jose's Bulletin #202 says the passage of time or a change of ownership does not legalize work done without required permits. That makes the permit record relevant to both seller and buyer, but it does not tell you the sale outcome or price. Your agent and attorney can address transaction and disclosure requirements for this property.