Onscreen Braille problems on XR: constant mistypings

When entering Braille characters on a brand new XR I constantly keep getting mistypes. Letter "w" is recognized as "j", "o" as "e", "s" as "i", etc. I'm certain I press all the necessary fingers because I specifically tested by both decreasing the entry speed and using other devices without any single error whatsoever. I've calibrated and re-calibrated, moved fingers closer to the different edges, tried to spread them wider, etc. with no apparent effect. Sometimes it takes me up to 3-4 tries to actually enter a symbol.
I thought maybe there is some option that needs to be disabled? Like pressing on the edges of the device and such. Maybe I'm missing something obvious? It also seems that there is no point in giving my iPhone to the Apple service? What's the chance it being with the controller?..
That absolutely weird problem bugs me to the extend that I'm about to attribute it to the particular device and get rid of it altogether. So, as a last resort decided to ask AppleVIS community for your educated input.
Thanks a lot in advance.
PS: The problem isn't language related, i.e. when entering Cyrillic letters the mis-recognition rate is pretty much the same.