In case those numbers are right, in the upper cases leaves an efficiency near 91%, because the motor only gets profit of the net power of the controller. The same applies for motor and gear train.
0,99 x 0,97 x 0,95 = 0,91
9% of 126kw sounds like a meaningful number in F1.
To clarify this: i guessed these numbers based on realworld numbers. 98-99% efficiency for straight cut gears is a common value.
The 97 and 95 are also purely based on guessing and common values. Al you pointed out, for total efficiency you got to multiply all efficiencies, what further brings them down. If you‘d want 95% total efficiency each of the three components should be at least 98.3% efficient (0.98^3 = 0.95).
I‘d assume that all teams are trying to to reach this and thus invest huge amounts of money.