Brake pedal sits too low

The pedal has a proper parking spot on the bracketry.
There are several ways the pedal can park too low on the factory bracketry. Do not drive it until you figure out why it is this way.
#1) is a too-short pushrod.
#2) is if the rear system is faulty. If the return springs are faulty, then the fluid that is supposed to return to the MC, after a brake application, won't. When the return springs, and the rest of the system is functioning correctly, the fluid returns and fills the front most chamber in the M/C, forcing the piston towards the driver, and pushes the pedal up to its parking spot.Anything that prevents the fluid from returning, will also drop the pedal. Like a collapsed rear hose, or rust in the line, or a faulty Residual valve, or a faulty Proportioning valve.Or a leak!
#3)If the M/C is prevented from returning to it's design parking spot, then the compensating port will not perform it's function, which is to allow fresh fluid to enter the system and compensate for that which remains in the system due to the disc brake pistons moving out, and staying out as the front pads wear.If this is allowed to continue, the pedal gets lower and lower, and one day I imagine, they would quit working.
#4)If the self adjusters quit in the rear, eventually you will be stabbing the pedal multiple times to get a hard pedal. What you would be doing is pumping fluid out to the rear. Also eventually, the pistons in a rear wheel cylinder can then pop out.You would of course no longer have any brakes in the rear. The pedal will drop and not return,but the car will continue to stop cuz the front (in a dual system, such as yours) is still working fine.

Now for #1,No biggie you can drive it til you fix it. But do not put a too-long push-rod in there. See #3
But with #s2 thru #4, do not drive it until you have proven the Cport is working, that there are no leaks, and that there are no faulty components in the system, especially hoses. Hoses often fail from the inside out. They often fail by delaminating internally. This may create a little check valve, which the returning fluid will activate , sometimes locking a brake, or brakes, in the applied position. And the resultant low pedal.