Payment of a bond to protect the OC in the event of damage to the common property as a prerequisite for an owner to commence renovations is not prohibited under the Act. It has nothing to do with a debt, it is a form of insurance. Note that if done properly the money would be held in trust, i.e. it does not form part of the OC funds, and if no damage occurs then the owner gets the money back.
Payment of a bond occurs in a range of scenarios and does not constitute not unjust enrichment.