Not debouncing on a MIDI keyboard
I guess the 1us RC lowpass filtering tries to keep off false keyhits caused by phones and other radio transmitters. The debouncing is performed with software. 

Do not add slowness to the circuit which detects if a key is pressed. Players hate delays. There's enough it already (MIDI transmission,communication between the MIDI interface and the computer application, sound generating DSP, sound system DSP, distance to the loudspeaker). As much as 20ms total in circuits (+ the distance to the loudspeaker) is well achievable by bad design and it makes a MIDI keyboard painful experience for a competent player.

Make your system to react as soon as possible to a keypress. Leave debouncing delay for the key scanning software and let it affect only to the time when the releasing of the key is taken into the account. Playing a sound a little too long is much less annoying than a delayed start. 

A simple debouncing strategy in software is to scan the keys say in every 3 millisecond if the caused 0...3 ms extra delay is not a problem. The maximum value 3 ms is equivalent with about 1 meter extra distance to the speaker which can be acceptable.