Hello, im new on tag editing, so i wanted to ask if i can change the name of a tag or that can only be changed by mods or admins?, cause there is a tag for a character that it would be referencing the wrong author.

The tag is called "hail_(medicalbiscuit)" the thing is, medicalbiscuit its not the owner of the character, it belongs to the artist 7th-r (on rule34.xxx) so it would be "hail_(7th-r)".

I have evidence, like the artist's X (twitter) where it is shown that the character belongs to him.
Proof: twitter.com/7thRanger

You should be able to change it manually by creating a new, correct tag, making it a character tag in the "Tags" screen, and then swapping out "hail_(medicalbiscuit)" for "hail_(7th-r)" where appropriate. The downside is this can't be done en masse and instead must be done individually on each pic.

That's where "My Tags" under "Options" on your account page comes in handy- Put both tags in there, save, and you can click to remove one then click to add the other, much faster than typing the same tag over and over again.

In future, please post any tagging questions you might have in the "Tag Discussion" thread stickied at the top of the page.