I know im a bit late but I am seeing problems with at least 2 records that are unbeatable.
One would be surf_this_njv which has a time missing 3 checkpoints by using a skip that cuts off most of the map where checkpoints are located, making the record unbeatable since the skip cannot be done anymore since you need to pass all checkpoints.
The second one may be beatable but was achieved with stage skips where you can bhop to the end of the stage without surfing the ramps, which you can no longer do since the stage speed caps dont allow you to do these skips anymore.
There are probably some more records/times out there that have prehopped skips or have skips that miss checkpoints that shave time that can no longer be used. I think this could be fixed by changing the maps with unbeatable times to either have less checkpoints or higher speed caps in stage zones.