If cracks in concrete foundations are by themselves evidence that the foundation cannot transmit the loads to the ground then why are building departments not regularly requiring foundations be replaced? Remember concrete cracks for a number of reasons and in most circumstances tight cracks are not a problem.R301.1 says that the structure shall be capable of transmitting all loads to the foundation. R401.2 says that the foundation shall be capable of accommodating all loads in accordance with R301.
If the foundation shows evidence that would make a "reasonable person" believe that the foundation is not in compliance with R401.2, it would be completely legal for a building official to require an engineer to evaluate the concrete cracking if it is in a structural member or foundation.
Given that concrete cracks I find it interesting that some individuals believe that the IRC means that an engineer need not be involved in designing the building but when cracks are observed that an engineer is required to address the cracks.