There is no way to adjust the velocity response. Source:
https://www.yamahasynth.com/ask-a-question/any-way-to-set-sensitivity-of-the-reface-cp-keys

... as to why the keyboard would respond this way - the thread above covers this assuming your playing is able to achieve a MIDI velocity of 1. This velocity is programmed not to trigger the tone generator. Similar to how slowly pressing a mechanical piano key will not make a sound either if the hammer does not have enough velocity to hit the string. If the end result is the "right" spot for this in the reface (in other words, if the amount of "slow" that doesn't make a sound on CP would or would not make a sound on a piano), I can't speak to.

You may want to check you have the latest firmware (v1.30) - although no firmware has been released to adjust velocity sensitivity.
https://usa.yamaha.com/products/music_production/synthesizers/reface/downloads.html#product-tabs

This velocity is programmed not to trigger the tone generator. Similar to how slowly pressing a mechanical piano key will not make a sound either if the hammer does not have enough velocity to hit the string

I haven't seen one synth or midi keyboard, that has similar setting.
Mechanical piano or E-piano works this way because of physical limitation, not on purpose.
I can't think of any reason to emulate this flaw, and I'm sure that it can be easily turned off by software switch.

Btw sorry for my English, i'm Russian.

There's a difference between - "can you play slow enough to notice you're registering a velocity of 1" -- which on other keyboards you have played, you may not be able to play that low of a velocity; and "the velocity of 1 should never be silent". According to the linked thread - many other keyboards share the same programming where velocity=1 does not trigger the sound.

I'm not sure if you indeed are (or are not) playing with a velocity of 1. That's something the MIDI output of the reface would tell you.

I would agree that if it takes a huge amount of effort to get past a MIDI velocity of 1 then there is an issue. There's a lot of "ifs" I've been throwing out.

That you have no adjustments is a problem if you're a light player (as you are). It seems you may have a reason to participate in ideascale in order to create or promote someone else's idea (by vote) to allow for velocity adjustments on the Reface CP.

https://yamahasynth.ideascale.com/a/dtd/Adjustable-velocity-on-Reface-CP/239505-45978

A week ago this idea was moved to "reserve". Here's what Ideascale says "reserve" is for:

This stage is built to help Administrators tidy up their communities by giving them a place to store dated, off-topic or on hold ideas. Rather than storing ideas in an active stage like Ideate, Refine, or Build Team, Administrators can now move ideas into a Reserve Stage which can be made visible or invisible for the community members.

... it stops short of saying this is a trash-can. It's possible that the request is not possible due to limitations in the hardware or software architecture. When items are moved into reserve - it'd be nice to have some commentary attached.

Thank you for your answer, and for the links!

I've recorded a video of this issue:

For me, playing on Reface is like walking in a mine field. It creates tension in hands, and very unpleasant.

According to the linked thread - many other keyboards share the same programming where velocity=1 does not trigger the sound.

That's may be the case, but Reface has springy small keys, compared to Motif XS/XF, MONTAGE/MODX which was provided as an example.
When I connect my old Yamaha PSR to CP, it's also not registering vel=1 notes, but it almost not noticeable because of larger keys and better velocity curve

I haven't seen one synth or midi keyboard, that has similar setting.
Mechanical piano or E-piano works this way because of physical limitation, not on purpose.
I can't think of any reason to emulate this flaw, and I'm sure that it can be easily turned off by software switch.

Many digital pianos work this way, in the name of authenticity. As far as I've seen, any digital piano with this "feature" provides no way to turn it on/off. It arguably has some use... you can silently depress keys, and if the keyboard employs emulation of sympathetic resonances, hitting other keys will yield an emulation of the resonances generated by the undamped strings assocaied with the silently depressed keys, as they would on a real piano. It's kind of more of a parlor trick than a musically useful device, IMO. I suppose there must be some avant garde piano pieces that make use of it, though. 😉

Watched the video. Feel sorry for you, Vlad.

That's horrendously unreliable, and yuk. You're obviously not absolutely babying it, so at those kinds of velocities it should be making a sound.

You can view scores of refaceCP YouTube videos by end users that do not behave as your unit is behaving. (It doesn’t even sound right - what sound is that?)

Recommend: check your power source, make sure you are using the proper adapter or change batteries (all batteries should be changed together).

Please just search the Internet for reface CP videos...several on this very site; you’ll see that your unit’s behavior is quite abnormal.
You are correct ...the action is very different from the MONTAGE, MODX, or Motif-series!