In theory, Dita was manufactured for that purpose.
You need to know about OS on Chi to get these response. The problem aren't if Chi are on Trans mode or not, the problem are if their OS have some backdoor for access. If these backdoor are present, there isn't important the trans mode, it's only the difference between ability of the attacker and the defender.
On real terms, think on that scene as two hacker working. One are attacking and another one defending. Probably the most important question here are the computer power itself, because Dita and Chi are AIs, the better processor can react before and do better.
Also, you need to think about the methods. Taking into account the above, probably Dita have more processing power than Chi (Because if you made a persocon for defeating another one, you need more power on them), but, Dita only have a basic AI and programming routines for doing their work, but Chi have some knowledge (Because have their learning program), and some feelings.
Probably no, Dita cannot defeat Chi, because Chi can learn about the attack, and use these knowledge for doing something.
But, there isn't any fact about this.