There is crumbling and then there is crumbling. Your inventory suggests that your house was built in the 1950s. The crumbling that typically occurs in houses of this vintage is caused by water migrating through the foundation wall, dissolving minerals along the way. When the moisture reaches the interior surface of the wall, it evaporates and minerals left behind, crystallize. The crystallization of these minerals (effluorescence), just below the surface of the concrete, causes spalling of the surface of the concrete. One can scrape off the loose concrete, andcoat the wall with a slurry of cement and water. The wall can then be painted with concrete paint, but as long as there is moisture migrating through the wall, the process will continue. Improvements must be made to the exterior grading, to ultimately solve the problem.
In many older homes (1920s and 30s) the crumbling is more severe. In many instances the walls were built with concrete which contained too much aggregate. To make matters worse, the aggregate was smooth, round, river bed gravel. That net effect is similar to making a cherry pound cake with too many cherries. In cases such as this, several inches of the thickness of the foundation wall can be lost. Repairs require the assistance of a structural engineer, as walls of this type have been known to collapse.