Looking at your numbers you bed is reasonably flat but it’s up at the front and down at the back. I wonder if some shims between the rail supports and the bed might work wonders. You would just need 4.
You can change M206 but it means the area you level will be shifted left and forward looking at the front of the machine. You also need to make sure you change it back before you do any printing. In addition the leveling is carried beyond the area measured and this can cause problems. As an example, if the measured points mean the nozzle has to go down towards the end of the measured area it will keep going down at the same rate so if your bed then goes up, it may hit the bed.
You also can’t use touch screen leveling as that puts M206 back to it’s current settings and you must make sure M206 is correct before printing as it’s not put back on power on.
I think @Brent113 is right and this is not your issue but if you want to try, this is my current levelling macro. Be very careful though, small steps and make sure you know what you are doing.
;bed level script bed heated to 65c
;bed heat is left on as usually doing a print after this.
G21 ;set units to millimetre
G90 ;set absolute positioning
M140 S65 ; set bed temp for bed level, heat while homing
G28 ;do this now, done in G1029 but takes ages
M190 S65 ; wait for bed temp
M206 x0 y0 ;remove workspace offset prior to levelling
M500 ;save change
;Auto Level
G1029 A ;start levelling
M114
G91; relative positioning for Z offset move
;*****************
G0 Z-xx.xx ;Device specific Z offset, reduce to bring print closer to the bed (bigger minus number). (equivalent to M851)
;*****************
M114
G1029 S ;save data
G1029 D0 ;end levelling
G90 ;restore absolute positioning
M206 x-19 y-10 ;Put workspace offset back on
M500 ;Make change permanent
G28; home all for safety
You need to put your own minus value in G0 Z-xx.xx. Do a touch screen levelling but take note of the distance you move the nozzle down and put the number here. Do small square test print to check the level and adjust with G1029 D-x.xx where minus -x.xx will bring the head down nearer the bed and positive x.xx will take it up. I move in 0.05mm steps.
I have also changed the firmware so it doesn’t switch off the heaters when doing a G1029 level but thats not crucial.
More detail of the idea behind this here but I now use this in a macro rather than have it in start GCODE.