Windmills do affect doppler weather radar. Concentrations of wind turbines (such as around Altamont Pass and in the Montezuma Hills) are clearly visible in Weather Service doppler radar maps as "red" spots that don't move around. Is that "messing" with radar? Depends on how you define "messing," and they're at ground level not flying around with transponders on. Airplanes routinely fly over the windmill areas in NorCal, and Tehachapi and San Gorgonio Passes, with no adverse effects. Note: air traffic control radar usually hits on transponders, which are required for nearly all aircraft in the US; windmills if they have any effect would be primary returns which are usually suppressed.

And who's proposing windmills next to the airport? And what does this have to do with HSR trains?

As for EMI from the trains, that's a solved problem elsewhere in the world. Lots of airports outside of the US have HSR in the basement or next to the terminal and don't have airplanes falling out of the sky.

As I read the articles about the BUR tunnel, the point is that the project has to be DESIGNED to meet that end-to-end time bogey (2:40 iirc). Thanks to sharing with Caltrain and detouring via Palmdale, the modeled time for an end-to-end express is uncomfortably close to that legally-required timing. So a (more) expensive tunnel than the shorter one closer to LAUS in previous work is now needed to straighten things out and gain a few minutes back. Coincidentally, it also makes a station *IN* the airport (rather than down the street) possible - not a bad thing in principle. If they would switch to one of the routes closer to Tejon Pass that have been studied, they could probably gain those minutes back without necessarily needing a tunnel under BUR. But that's another story ... and having committed to a Bakersfield station next to the UP line, near downtown, they've pretty much committed to the Tehachapi-Mojave-Palmdale route.