To reproduce:

• Try translating "User:Amire80/link list test" from zu to en. (It includes an external link that appears in the English Wikipedia's spam blacklist.)
• Try publishing.

Observed: A large and hard-to-read message is shown:

An error occurred while publishing the translation. Please try to publish the page again. Error: {"code":"spamprotectiontext","info":"Hit AbuseFilter: ","warning":"<table id=\"mw-spamprotectiontext\" class=\"plainlinks fmbox fmbox-warning\" role=\"presentation\"><tr><td class=\"mbox-text\">Your edit was not saved because it contains a new external link to a <a href=\"/wiki/Wikipedia:Spam_blacklist\" title=\"Wikipedia:Spam blacklist\">site registered on Wikipedia's blacklist</a>. \n<ul><li> <b>To save your changes now</b>, you must go back and <i>remove the blocked link</i> (shown below), and then save.\n<ul><li>Note that if you used a redirection link or <a href=\"/wiki/URL_shortening\" title=\"URL shortening\">URL shortener</a> (like e.g. 'goo.gl', 't.co', 'youtu.be', 'bit.ly'), you may still be able to save your changes by using the direct, non-shortened link - you generally obtain the non-shortened link by following the link, and copying the contents of the address bar of your web-browser after the page has loaded. </li>\n<li> Links containing 'google.com/url?' are resulting from a copy/paste from the result page of a Google search - please follow the link on the result page, and copy/paste the contents of the address bar of your web-browser after the page has loaded.</li></ul></li>\n<li> <b>If you feel the link is needed</b>, you can: \n<ul><li> <i>Request that the entire website be allowed</i>, that is, removed from the <a href=\"/wiki/MediaWiki_talk:Spam-blacklist#Proposed_removals\" title=\"MediaWiki talk:Spam-blacklist\">local</a> or <a href=\"//meta.wikimedia.org/wiki/Talk:Spam_blacklist#Proposed_removals\" class=\"extiw\" title=\"meta:Talk:Spam blacklist\">global</a> spam blacklists (check both lists to see which one is affecting you).</li>\n<li> <i>Request that just the specific page be allowed</i>, without unblocking the whole website, by asking on the <a href=\"/wiki/MediaWiki_talk:Spam-whitelist\" title=\"MediaWiki talk:Spam-whitelist\">spam whitelist talk page</a>.</li></ul></li></ul>\nBlacklisting indicates past problems with the link, so any requests should <b>clearly</b> demonstrate how inclusion would benefit Wikipedia.</td></tr></table>\n","result":"Failure"}

Not only is it hard to read because of all the JSON and the markup, it doesn't include the most important thing: What link is actually causing the trouble.

Expected: Something like this: "Your translation includes a link to http://anglianhomes.co.uk, which is forbidden in the English Wikipedia. Please remove it before publishing." It would be an excellent bonus to also show where exactly does this link appear in the translation column.

Reported by a user at https://www.mediawiki.org/wiki/Topic:T77htyt01wwy9750 . (The link in the test page was randomly picked by myself from the English Wikipedia spam blacklist. It's not related to the link about which the user was speaking.)