I just want to follow up on this issue again since we were dealing with it recently. What we did to apparently resolve the issue is to simply pull a backup archive from a time before and update the spatial index, The issue does not seem to occur anymore
Based on this, my question here is can spatial index potentially corrupt the feature class within the FGDB if not updated accordingly?
I was reading the suggestion below on when to update the spatial index and it states that re-creation of the spatial index is recommended only after you have added a large number of feature that differ in size from the features that are already in the feature class. This applies to adding features in edit sessions only.
ANY write operation, if it fails, can corrupt a file geodatabase. Actual media failure is more likely the cause, especially when the FGDB is on a networked device.
The instruction to rebuild the index after a high volume of inserts is more likely to prevent fragmentation in the index, not related to corruption.