I don’t know about your inverter but the Sol-Ark is running at the Value of the Grid so long as the Grid stays within the Min/Max Values. If the Grid is not being used it Runs at the Nominal Value I set for operating voltage which in my case is 240/120V. If it’s operating within the Max and Min parameters it’s fine and the voltage will Rise or Fall with the Grid but if they are exceeded it then it switches to Battery until the utility voltage stabilizes.
Here is The Inverter during a Blackout and it has gone exactly to my Nominal voltage value.
View attachment 203054
Here is the measurement with the Grid Back but still low but within my Minimum Value.
Note it is not trying to compensate for the 114V.
View attachment 203055
Sorry but I can't find a graph with High Grid voltage, but I have seen it and if the Grid is at 250/125V the inverter outputs 250/125V. It will only react when the voltage passes the Maximum set point on the Inverter. If I was selling back to the Grid it would Increase the voltage slightly higher than the 250V.