The crossfader’s response is not so good.

Is the DDJ-RX’s "CROSS FADER CURVE selector switch" set properly?

Turning the "CROSS FADER CURVE selector switch" fully clockwise results in a sharply rising curve.

With DDJ-RX, you can adjust the crossfader cut lag in 53 steps in the utility mode. For details, see the operating instructions of DDJ-RX. You can download the operating instructions from the support page.