Hi,
Normally yes you must be able to change the flashing rate ..
This is the lights (aircraft.cfg) of the Wilco ERJ 135 V2
[LIGHTS]
//Types: 1=beacon, 2=strobe, 3=navigation, 4=cockpit, 5=landing
light.0=3, -12.20, -31.99, 2.35, fx_navred_E1X5 ,
light.1=3, -12.20, 31.99, 2.35, fx_navgre_E1X5 ,
light.2=2, -11.8, -31.99, 2.35, fx_strobe_E1X5 ,
light.3=2, -11.8, 31.99, 2.35, fx_strobe_E1X5 ,
light.4=1, 12.70, 0.00, 9.00, fx_beacon_E1X5 ,
light.5=1, -5.00, 0.00, -1.30, fx_beacon_E1X5 ,
light.6=10, 30.50, 0.0, 4.00, fx_vclight ,
Those FX files are effects and are located in the FS gauge folder
You can rename those files as TXT .. like fx_strobe_E1X5.fx
fx_strobe_E1X5.txt so you can edit in Notepad.
BUT !!! I dunno wich parameter apply to the flashing rate !!
It also a other solution .. swapping of effect !!
EG .. if you have a good rate (for you) flashing beacon from a other AC .. like :
FX.blabla.fx .. you can rename the fx_beacon_E1X5 as FX.blabla in the aircraft.cfg lights of the ERJ .....
Never forget to save anyting before make changes.