I am a public sector accountant, so not sure whether my advice is worth much to you. Because it is for a tribunal, I have to say that this is just an opinion - please don't rely on it.
However, just as an objective bystander, it sounds like this to me:
The trading profit is something within your sphere of influence, something you can control, and something your decisions have made a difference to.
The rest depends on whether the trading differences and exceptional costs are also something within your control. If exchange rates have deteriorated, beyond that which could have been reasonably forecast, and this has an impact on your net profit, then you have a mitigating argument as to why that has happened. It depends on whether this is something you are expected to be able to make a difference to.
If there is nothing you could have done to influence that, then how can you be held accountable for it?
Again with the exceptional costs, if they were down to your decisions, then you have to take responsibility for them, but depending on what they are, they might be outside your scope.
The issue of whether they were budgeted for is probably down to timing. If they should have been budgeted for, because they were predictable, then this is a factor. For example, if they were budgeted for in other areas, or if you were asked to submit a forecast for them and didn't.
I think there is an important principle of delegated authority and autonomy. You can only be held accountable for the things that you are in control of.
Good luck.