Yeah, Misaka has EM sense which allows to sense electricity. Though there is a scan from the manga with Misaka dodging a near point blank electron beam but I haven’t read the Railgun manga so I don’t know if that’s a legit reaction feat or something done EM sense.So basically they are actual lightspeed attacks(atleast Mugino's are) but due to being able to sense and redirect them, they aren't at that level of speed right?
Also Misaka’s lightning may be lightspeed to cause in volume 1 her lightning is said to move at the speed of light. And I think this is said in volume 3 as well.