Frame data for f3 fully charged is wrong. There's a fair few moves that it looks like they just didn't bother to write frame data for so all of the values are listed as 1 or -1, this is one of those moves. I've done a tiny bit of testing and it looks to me like the fully charged f3 is -4 on block just like the uncharged one is, at least at closest range.
The reason you were able to knock reptile out of the slide after the blocked f3 even though you should've been a few frames down I think is because A) you hit reptile later in the active frames of the attack (6 active frames for f3 means if it's -4 on frame 1 then it is actually +1 on frame 6) and also slightly because B) reptile's slide must move forward before it can hit you, therefore not hitting on its first active frame.
One other thing to consider is that standing 4 isn't quite as useful if your opponent respects the frame trap. D1 will whiff if your opponent doesn't attack after blocking the 4 , so you can't sustain the pressure and your opponent has a huge gap to backdash, jump or whiff punish once they know where the opening is.
Also 112, f2, 24 and b32 into tele cancel are all at least +2 and b1xxtele cancel is at least +5. It is tricky to do these consistently and they require stamina, but they are much more useful frame traps I think.
