I am not using the Jailbroken version so I cannot comment on the OHK feature. When DiDa released the Non-Jailbroken OHK ipa, I tested it out on various end-game accounts I had bought. From what I concluded, OHK is a high-risk feature and will result in a permanent ban. On the ViP non-jailbroken version, most current ipa, probably effects memory in some shape or form so i would guess that they check for memory manipulation along with time stamps, hits received, etc. The odds of a packet returning flagged on a fight with a 4* max sig against a 5* high sig is high if you've received no hits, and time stamp shows enemy was killed in a minute, etc.
How long have you been using OHK in arena? Also, how long ago did you complete 5.2?