Yep they are pretty bad.

There are a couple of things you can to.
1.

If it were mine I would create and airlayer and bury it deeper. Take it out of the bonsai pot for a season or two.

Look up how to airlayer on wiki here.
2. If you don't want to do that, remove anything crossing and all the back dead and rotten roots and bury it deeper. Again out of the bonsai pot. For a season or two.
Nebari should only be shown if it is good nebari and this is not and never will be by being exposed like this.
Small roots like this that are exposed are too weak to develope into good nebari. Usually they just dry up and rarely thicken.
if it were mine I would go option 1. For long term improvement
Wal,

it would like like its growing on stumps. Not a good look! And would not improve the nebari at all
Cheers
Kirky
Great oaks from little acorns grow.