Translation:This is a very historic painting, it would be very bad if you touch it.
I see that the missing comma was pointed out 5 years ago already. It makes the Turkish sentence VERY difficult to break down, it would be nice if someone fixed it.
In addition to that, I think that the literal translation of the English sentence would be "bu çok tarihi bir resim".
Finally, why is "onu" missing as the object of dokunmak?