There are no real "burst safe" combos for Ragna, designed to bait bursts, as far as I know. But, I've used the following for baiting bursts before:
-Jump cancelable normals (5C, 3C, 6A, air normals, I JC them on hit and block the bursts in the air)
-Deadspike (Ragna recovers in 14 frames, so if they burst it as it hits, you can block)
-Blood Kain activation followed by a jump cancel able normal.
-Fatal counters (If you don't follow up into anything, you can block after the 2C and bait their burst. If they don't burst, you can follow up with 5A or 5B after the 2C recovers to continue a combo)
There's probably more, but those are some ideas you can use to bait bursts.