Posted 25 MPH speed limit is not legally enforceable per vehicle code 22359. The side of the road that is in Los Altos has a 25 MPH limit; the side that is in Mountain View has a 30-35 MPH limit, depending on location.
Vehicle Code 22359 says that if two sides of the road are in different jurisdictions they must agree on the posted limit or both posted speed limits become unenforceable. With both traffic surveys invalidated, the legal speed limit reverts to 55 MPH (per vehicle code 22349) for a two lane undivided highway with no legally valid traffic survey justifying a lower speed limit.
Los Altos lowered the speed limit based on the change to the wording of vehicle code 627, however 627 only defines an engineering and traffic survey. It is vehicle codes 22357 & 22358 that give the City the right to post a reduced speed limit as a result of the survey, and 22359 clearly invalidates that limit with different speed limits posted on the Los Altos in Mountain View sides.
As a side note, I do think the speed limit on Springer should be somewhere between 25-35 MPH, but I find it ridiculous that the City Council held discussions on changing the speed limit when apparently no one on the city council, or none of the attendees, even bothered to read the applicable vehicle code first. State laws take precedence over city ordnances.