FOC Iq peak current overshoot
Unfortunately PI cannot predict the dynamic change reversal in force that switches it from generator to motor mode and you need to incorporate Differential gain, Kd, to anticipate the change to reduce overshoot.  Changes to PI gain may also be necessary slightly as Ki gain stores some history according to it’s time constant.
The surge current will be proportional to the tradeoff allowed for speed error and current overshoot as RPM load regulation depends on the ratio of load torque to available counter motor-torque.  If you specify your permitted load regulation error in RPM and current overshoot, you may be able to meet spec. But these are trade offs.
The grid operates the same way to load changes but at a much slower rate of change in RPM or Hz in order to maintain voltage regulation with field current at the new demand power levels within 5% V and 5% f slowly changing (estimated not from grid specs). These trade offs are determined by design of excess capacity. In areas with excess power capacity, in isolation, RPM can be caesium clock synchronized , which was the case in Winnipeg during the late 70’s when I verified with 1e-10 frequency counters for 60Hz. Thus is just an analogy to your problem.