How many targets can a sea sparrow launcher target at the same time ?
Are they effective against mass air attacks ?
E.g an average 80s destroyer has 2 sea sparrow launcher, can they take out an entire squadron of attacking aircraft armed with PGM ( assume the aircraft is a 80s VVS or AVMF su24 or mig27)

a LAUNCHER doesn’t target anything, you need to look at the fire control system: how many illuminators and are these necessarily continuously illuminating targets? In the Dutch navy, there typically were 3-4 channels (2 big Stir 2.4, sometimes plus 1 smaller STIR 1.8, and CAS/WM-25 dome).

Sea Sparrow has been fired from at least three different launchers: a modified ASROC launcher, the Mk29 GWLS and vertical launch (Mk48).

See e.g. https://en.wikipedia.org/wiki/Mark_92_Guided_Missile_Fire_Control_System
This is on the Perry class (SM1) but the principle is the same as SM1 is semi active radar homing too.