Im kinda experienced in this matchup because my main training buddy is a jin. First, always punish his ice cars, IB or just block them but try not to barrier them specially if is in a block string cause they will get to far for 5B to reach them. If they dash cancel, punish them too... they will try to do it some times and its totally unsafe if they are not a maximum reach. Keep your guard down as much as you can, just watch out for the overheads, which are very slow.
try to keep them in 5B range cause thats your safe spot. Always keep pressure and dont give them any space to breath.
For aproaching, IAD is a bad idea, they have too many anti air options/fast overdrives. Keep yourself grounded and ID them if they try the air aproach but do it sparringly, cause you dont want to be instant blocked a get punished.
They have great pressure strings so try to barrier a lot and dont get too close to walls cause they have a very safe pressure string that will guard crush. Dont get randomly grabbed or frozen because that will cost you the match.
The easiest way for ragna to win this matchup is to control the tempo, if you get that, then the match is yours.