How to repair an OPEN FOUNDATION home?
Depends what you have to work with, pier/post wise.

Also depends how much "fix" you want given that the foundation is moving, unless it was just poorly built at the start.

If you have enough extra post above where the rough 2x10's are bolted in, you support, unbolt, level (slowly....) then drill and rebolt.

If not, you can do the same, but lower all to match the lowest one, trimming off the post tops if they don't have room to move up.

Alternatively, you could probably "sister" the piers/posts so that you could raise the 2x10's

If you actually want to address the inadequate footings, you have to support the house, then remove and rebuild the footings and piers. Which is quite a bit more work...