Pressure altimeter sources are typically highly precise, but notoriously inaccurate. Even altimeters on IFR rated aircraft have an allowable +/- 75’ tolerance when compared to a known elevation. If your barometers are agreeing within a foot, I’d say you’re getting outstanding data.
You’re absolutely right about the altimeter accuracy requirement for civil aviation. (VFR and IFR if I remember correctly)
But being new to sUAS and Cube flight controllers, I had no idea what the acceptable allowances might be.
I don’t remember seeing anything in the docs about checking barometers in the tuning guide. I’m guessing that if EKF is synthesizing an altitude from available inputs, consistency matters more than accuracy - especially when operating in “relative” reference to terrain.
I’ll make a post to the folks at Cube Pilot and ask them how closely to expect the barometer alignment - and when to be alert for trouble.
In the mean time, I’ll try to remember checking this in the future when I implement a new flight controller.