I came from old days in tagging in danbooru, and there, the tag aliases worked well. Here, they don't seem to work quite so well. That is, there are many similar tags that have preferred aliases, but the non-preferred tags get added to the posts anyhow. Also, if you mistype the same tag twice on a new posting, it adds duplicate tags to the post. Then when tags are updated later, the duplicate tags finally drop off.

With that being said, it seems like the booru software running xbooru seems to be out of date. Are there any plans to update the code so tag management will work more smoothly?

We are aware of the issues and the site owner has been looking into ways of improving the tag system.

I believe Slayerduck has been thinking of upgrading to the new software version (gelbooru 0.2.5 opposed to the current version of 0.2.0 we run). We do know of the issues as Kielan stated and are looking to correct them.