As Kermit says, they are separate issues. You have confirmed the replacement accumulator has fixed the pump running every brake press. Brake lights on the back of the car are most likely the pedal switch - reset the adjustment, or replace it...

I suspect you still have airlocks in there ? You could also put the sensor in boiling water & see what your diag tool says then ?

3 glowplugs wqere replaced last year. The one in cylinder-2 is still stuck fast in the engine. But these should only impact starting, and not running whne engine is warm. EGR blank arrived & waiting for FIP & Regulator seals - these will be...

or a thin spanner

+1 on this. Did you remove both sodes at the same time ? If so, thats why the asle rotated a bit.

If the header tank cap is tight with no leaks, I would say until you release the pressure. more likely is a slow depressurise through the pump (unless it has a suitable valve ?)