Another source for additional docs and local hearings is the Sanford Lake Association webpage. Documents are available on the the Sanford Dam tab (linked) and the Edenville Dam tab.
https://sanfordlakeassociation.org/sanford-dam
From google maps aerial images, can see the how the existing gates and spillway near the powerhouses are not much larger than the incoming river. Dams date from the 1920's and gates and spillways were often designed for only minor flood events, prior to 100 year and 500 year storm event standards.
From the flood pics and videos, appears the "failure" was the lakes exceeded capacity from the heavy rains and began spilling over the dam crests. Overflow then scours and erodes the dam embankment. The gates and spillways were still intact during the flood event. So failure appears to be overflow, not structural.
Over the decades, government agencies have been reluctant to invest in upgrading dam gates and spillways as there is no tangible return on the investment. Government waits until some work is planned and as part of the permit process will require additional work such as increasing gates and spillways. In addition to the costs, it often requires lowering lake levels which can hinder permitting. So no permit from the governments results in no work to upgrade. That occurred with Edenville. Aerial video show the gates are the same as 2018 plus the Sanford Lake docs show the permit for work was revoked.
ASCE has rated dam infrastructure a "D" for decades. Wasn't part of 2009 ARRA for rebuilding the nation's infrastructure?