Not sure I have the correct picture from your description but if the "twisted" chainplate is to one of the uppers and if the "twist" in the top of the mast has resulted in some glue line failure, then it sounds as if the damage was caused by that stay/chainplate snagging and wrenching. I'm basing that on observation of similar damage caused by a moving boat snagging a stay on a protrusion from a pier.
Minimum, that stay and chainplate are history. The top of the mast should be rebuilt in the normal way - cloths pin scarf. The whisker stays and bobstay probably need renewal. But as for the other stays - if they are old enough that one would even think of replacement, now's the time. If they are relatively new, give them a very close inspection.
G'luck
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