1 option besides fixing the actual problem or trying to find a specific parameter to say adjust the spindle speed from what is commanded is to call a macro program via S() command and change the spindle speed in the macro to compensate.

I am not 100% on your control but IIRC take a look at parameter 7000.1 (SCS bit) which if set will call a macro program every time that S() is commanded in your program. I do not recall which program number it calls but it should be in the 9000 range. Some controls only allowed the T() command to call a subprogram and others would allow both S() and T() I will have to dig thru the basement to see if I can find any of my older 10series manuals to confirm.

Anyhow if you can call a sub via S() command then you can program the different spindle speed inside the program so as an example if program 9000 is called via S500 but the spindle speed wants to run 3x then programmed you can then in the 9000 program write
#19=#19/3
M3#19
M99
When setting this parameter and calling the sub it will set #19= to the modal S() value so in the program take the value divide by the amount of the over shoot and then reprogram the M3 to that value.

Stevo