Script I use to convert artists bookmarks into ___booru artist's names (remember to customize this script to fit your bookmarks file).

bookmarks2artists.py

import json, requests

with open('bookmarks.json') as file:
	bookmarks = json.load(file)

saved = []
error = {}

for bookmark in bookmarks:
	url = bookmark['uri']

	artists = json.loads(requests.get('https://danbooru.donmai.us/artists.json?search[url_matches]=' + url).content)
	artist = [artist['name'] for artist in artists]

	print(url + ': ', end='')
	print(artist)

	if len(artist) == 1:
		saved += artist
	else:
		if artist:
			error[url] = artist + [bookmark['title']]
		else:
			error[url] = bookmark['title']

with open('artist.json', 'w') as saved_file:
	saved_file.write(json.dumps(saved, indent=2))

with open('error.json', 'w') as error_file:
	error_file.write(json.dumps(error, indent=2))