How could a change of investment projects impact the status of a dependent in an EB-5 case?

They cannot change the investment now. The new regulations may allow for a change of investment and keeping the priority date, but a whole new I-526 petition would still be necessary.

If the principal has already obtained conditional permanent residency, then some level of change is permissible, or at least USCIS is more lenient. However, if the jobs were not created, then USCIS can go back and revoke the petition approval.

Potentially.

When you say the principal investor changing the project, do you mean changing the regional center? This might even disqualify her. Your application is tied to the principal investor. If this material change affects the principal investor it would, unfortunately, affect you as well.

Your status as a dependent depends on the status of the principal applicant. Regarding the change of investment, I would be very careful in making any changes to the status quo at this time. If you have to, look at the exit strategy or options you had when you signed up with the regional center.

Your status is entirely contingent on the lead petitioner and your eligibility is tied to him/her as well. If a material change impacts the lead petition it can certainly ripple out to you. Unless USCIS has made a formal decision, however, there has likely been no finding of material change. Thus, it may be your best interest to enter as soon as possible if that is the case.

This would depend on the facts of the case. It will require a careful analysis.

It will not necessarily jeopardize your application. You qualify as a dependent not on the project per se. In any event to keep funds at risk the PPM may provide for such change.