>>/957/
I do not know much about this myself, but I think this is the current guide:
https://github.com/CuddleBear92/Hydrus-Presets-and-Scripts/tree/master/Downloaders/Gelbooru

If you did that and it still doesn't work, I guess hit network->data->review session cookies and then clear everything and try again.

 >>/958/
In hydrus, pend is add, petition is remove. Let's say you open a manage tags dialog on 10 files, 6 of which have 'character:samus aran'. You then double-click that tag. You then have the options:

pend samus to 4 (add that tag to the other four that don't have it yet)
petition samus from 6 (remove it from the six that do have it)

The terms 'pend' and 'petition' are different from 'add' and 'delete', yeah, because when you are talking to the PTR, all changes you make wait in the 'pending' menu up top. They only actually become 'real' when you commit by uploading to the server. You get the little (+) and (-) symbols after the tags, meaning they are 'waiting' to be added/deleted.

Thank you, I will clean up the help on this, and the UI.

 >>/960/
 >>/961/
Encryption is notoriously difficult to get right. I am not confident I can do as good a job as third party programs, so I strongly recommend you figure out a solution using one of them. Hydrus works completely fine out of a mounted encrypted partition as ciphershed-style software will create.

Syncing to a remote server is not as simple in this situation, but perhaps a program that encrypts individual files would fit into your workflow. Or if your remote connection is secure, and the client and server are also operating out of encrypted containers you trust, it may work.

It is generally not safe to touch the database file while the client is running. I know google-cloud backup has corrupted a hydrus database it was watching. I recommend you only do backups while the client is shut down.