Have you trammed the X axis? Looks like there’s a consistent slope from side to side.
Do something like this photo and repeat?: Carriage Tolerances - Unusable Over Distance >75mm From Center
I’d expect your side to side deviation will be smaller.
I massaged your numbers and got a maximum deviation of 0.657mm
To get that I computed the average slope (0.139mm/sample from left to right) and subtracted the slope off the measurement of each point.
Delta L-> R
+0.209 +0.161 +0.184 +0.146 +0.122 +0.110 +0.054 +0.058 +0.072 +0.038
+0.171 +0.128 +0.161 +0.138 +0.098 +0.148 +0.117 +0.075 +0.100 -0.045
+0.223 +0.142 +0.177 +0.133 +0.118 +0.156 +0.104 +0.110 +0.121 -0.019
+0.190 +0.177 +0.168 +0.150 +0.140 +0.141 +0.108 +0.148 +0.095 +0.040
+0.208 +0.147 +0.190 +0.167 +0.111 +0.168 +0.131 +0.115 +0.149 +0.080
+0.228 +0.175 +0.189 +0.136 +0.132 +0.172 +0.128 +0.123 +0.127 +0.102
+0.218 +0.188 +0.180 +0.157 +0.139 +0.156 +0.124 +0.123 +0.120 +0.086
+0.234 +0.175 +0.189 +0.161 +0.146 +0.167 +0.098 +0.123 +0.132 +0.044
+0.248 +0.179 +0.203 +0.170 +0.149 +0.161 +0.109 +0.141 +0.094 +0.015
+0.226 +0.182 +0.218 +0.188 +0.144 +0.155 +0.126 +0.122 +0.128 -0.010
+0.206 +0.203 +0.216 +0.214 +0.160 +0.140 +0.109 +0.122 +0.105 +0.083
Average Slope
+0.139
Slope Corrected Measurements
+6.216 +6.286 +6.307 +6.352 +6.359 +6.342 +6.313 +6.227 +6.146 +6.079 +5.978
+6.512 +6.544 +6.532 +6.554 +6.553 +6.512 +6.521 +6.498 +6.434 +6.395 +6.211
+6.483 +6.567 +6.569 +6.607 +6.601 +6.580 +6.597 +6.561 +6.532 +6.514 +6.356
+6.481 +6.532 +6.569 +6.598 +6.609 +6.610 +6.612 +6.580 +6.589 +6.545 +6.446
+6.450 +6.519 +6.526 +6.577 +6.605 +6.577 +6.606 +6.597 +6.573 +6.583 +6.524
+6.438 +6.527 +6.562 +6.612 +6.609 +6.602 +6.635 +6.623 +6.607 +6.595 +6.558
+6.405 +6.484 +6.532 +6.573 +6.591 +6.591 +6.608 +6.592 +6.576 +6.557 +6.504
+6.358 +6.453 +6.488 +6.538 +6.560 +6.567 +6.595 +6.553 +6.537 +6.530 +6.435
+6.278 +6.387 +6.426 +6.490 +6.521 +6.531 +6.553 +6.522 +6.524 +6.479 +6.355
+6.192 +6.279 +6.321 +6.400 +6.449 +6.454 +6.470 +6.456 +6.439 +6.428 +6.279
+6.057 +6.124 +6.187 +6.264 +6.339 +6.360 +6.361 +6.330 +6.313 +6.279 +6.223
MAX MIN DEV
+6.635 +5.978 +0.657