The only cause I recall of the Flight Director indicating too great a pitch during takeoff/climb was a throttle axis spiking issue. That's covered in my previous response in this thread, along with a potential workaround for that.
Another way of working out if it is throttle axis spiking related, will be to temporarily unplug any external hardware with a throttle axis assignment from your PC (joystick, throttle quadrant, etc.) and then load a flight in the RJ on the runway. With a flight loaded on the runway, enter a flight plan in the FMS takeoff as normal. If the flight director bars indicate 8 degrees pitch up for the takeoff roll, and then indicate the pitch required to maintain V2+10 during the initial climb, then they are behaving as expected and the cause will likely be related to a spiking issue in the throttle axis.
If the issue persists with no throttle axis assignment in play, the could I kindly ask you to raise a ticket with Just Flight Support via the following link: https://www.justflight.com/support
In the support ticket, if you could supply a video of the behaviour, then our support team will have the best chance of either reproducing that behaviour and be in the best position to assist with further troubleshooting.
Mark - Just Flight