A new textdomain called wesnoth-tools has been added as of 1.17.18. This textdomain is for newly translatable strings for Wesnoth's python tools and was added in
https://github.com/wesnoth/wesnoth/pull/7627. However, the strings in that tool are not of a good enough quality that they would be worth translating as-is. Therefore, this textdomain shouldn't be translated until
https://github.com/wesnoth/wesnoth/issues/7724 is resolved, and it won't show up on gettext.wesnoth.org until then as well.