I've noticed that there's a tag "sanding" that is obviously peoply mistyping "standing". I checked every picture and it doesn't seem any of them have actual sanding going on so my question is this: Is there a way to mass change this one tag to "standing" in order to avoid going through each picture individually?

If you want to check for yourselves:
gelbooru.com/index.php?page=post&s=list&tags=sanding

You can edit them yourself if you feel like it and there's not a lot of them, but you can also post about it in the Gardening thread to let them know and someone will fix it: gelbooru.com/index.php?page=forum&s=view&id=1706 The mods have access to a mass tagging tool, so they can fix really large messes quickly. People in the unofficial gardening group don't have delays between edits, so they can go through smaller sets and fix them more quickly than those of who aren't in it.

Thank you! That's exactly what I was looking for but now I checked and someone has already fixed the issue!