We've just had to unbuild several hundred work orders due to a QC issue. After doing so, the associated order lines still show committed. This seems like a bug/defect, as stock can't be committed when it no longer exists. Is there any process to clean this up without editing every sales order?

Did you delete Assembly Builds/Work Order Issues or did you use the Assembly Unbuild transaction? If you did option 1, you essentially put the WO back into a pre-build state which means it's waiting issuance of material and therefore has commitments.

We've actually found the opposite. Unbuilding leaves the sales order line committed, deleting reverts everything to the situation pre-build.