You should probably put the dampening on the Blendspace itself, using a “Target interpolation rate” setting inside the blendspace for that axis.
You CAN apply the damping directly to the variable using an FInterpTo node but it’s more complicated to set up than the sample interpolation smoothing in the Blendspace directly
EDIT: also, make sure you’re properly applying Delta Seconds to that DeltaYaw variable! Delta Seconds is the elapsed since last frame, and you know the rotation rate since last frame… If you know Seconds / frame and Yaw / frame, and you want Yaw / Seconds, you would divide the value you feed DeltaYaw by Delta Seconds before setting it. This will produce a much smaller value which should also be far more consistent from frame to frame.
That doesn’t mean you don’t want to interpolate, but if you see a lot of jittering delta compensation is like a magic bullet.