What can I do if the bidder adjusts the Schedule of Quantities in the tender?

We cannot offer legal advice; however, the Preparation and Award Checklist in the User Guide and our Contract Considerations videos might help you interpret the documents and processes.

Is there recourse for the Contractor when an Owner Caused Delay affects Substantial Completion?

The User Guide (10.3.2.1, 10.3.2.2) suggests that Owner caused delays (per GC13.1) entitle the Contractor to reimbursement for costs and lost time. In this case, the CA must act impartially and issue a Change Order for the proven impact, even if the CA was the cause of the delay.