They have a digital dash so will be a speed sensor on that.
If it's only reading half of actual speed then it will probably just be a sensor issue, or it could be whatever actuates the sensor. Might be a pair of magnets and one of them is missing.
No I didn't book an evening session. Did donington in July and went to blyton Park for an exclusive triumph day in August which was awesome. Joined by Brandon Paasch from triumphs British supersport team as well