As far as I know there are no aftermarket springs for Alps style switches, so you're stuck with the default strength. If you want quiet tactile switches with soft springs you could get a Poker II with Clears and put 62g springs in or if you want even softer, Browns with even softer aftermarket springs.
MX Reds have around 45g pressure to the actuation point, increasing to almost 60g at bottom out. Matias are around 65g at actuation and the resistance stays low after actuation so it's still less than 65g at bottom out. Even if you could fit Red springs in a Matias switch, it would still have around 60-65g actuation pressure due to the design of the mechanism.
MX Browns actuate at around 55g then the pressure drops to around 40g, builds to 50g quite quickly and then slowly increases to 60g at bottom out. With some lighter springs in Browns you can get really soft tactile switches.
One of the primary advantages of MX switches is their "tunability". If you're already opening switches to swap springs, I would highly recommend doing the trampoline mod (with silicone balls from IMSTO for instance) if you want a quiet and soft bottom out like the Matias quiet switches. Another advantage is the ability to use a wide range of keycaps on them, increasing your options to adjust the feeling of your keyboard to your taste.
