External transformer for PCB made for someone else a few volts higher than circuit was designed for, will this damage the optoisolators?
LTV817 is good for up to 50mA through the LED, so there should be no problem with 22mA (ballpark) instead of your designed 20mA.
The LED will age slightly faster but if the switches are normally open momentary switches this is unlikely to be significant.
Line voltage is not constant and thus ac supplies produced using a transformer also vary so it is good practice to allow for some variation in the supply voltage.