API error responses generated by AbuseFilter and SpamBlacklist have changed, as announced here: https://lists.wikimedia.org/pipermail/mediawiki-api-announce/2019-September/000148.html (relevant task: T229539).
It appears you have special handling for the old responses. It should be updated, otherwise it will probably show a generic error message instead of a more specific one.
extensions/ContentTranslation/modules/mw.cx.TargetArticle.js:
222: // {"result":"error","edit":{"spamblacklist":"facebook.com","result":"Failure"}}
223: if ( editResult.spamblacklist ) {
225: mw.msg( 'cx-publish-error-spam-blacklist', editResult.spamblacklist ),
230: // Handle abusefilter errors.
231: if ( editResult.code && editResult.code.indexOf( 'abusefilter' ) === 0 ) {
extensions/ContentTranslation/modules/eventlogging/ext.cx.eventlogging.translation.js:
26: mw.hook( 'mw.cx.translation.abusefilter' ).add( this.logAbuseFilter );
122: var abuseFilterCodes = [ 'abusefilter-warning', 'abusefilter-disallowed' ];
129: trace.edit.abusefilter
138: trace.edit.abusefilter.id
extensions/ContentTranslation/modules/eventlogging/legacy/ext.cx.eventlogging.translation.js:
220: var abuseFilterCodes = [ 'abusefilter-warning', 'abusefilter-disallowed' ];
227: trace.edit.abusefilter
236: trace.edit.abusefilter.id
extensions/ContentTranslation/modules/publish/ext.cx.publish.js:
299: // Handle abusefilter errors.
300: if ( details.edit.code && details.edit.code.indexOf( 'abusefilter' ) === 0 ) {
305: // {"result":"error","edit":{"spamblacklist":"facebook.com","result":"Failure"}}
extensions/ContentTranslation/tests/phpunit/AbuseFilterCheckTest.php:
107: [ 'disallow' => [ 'abusefilter-disallow' ] ],
109: 'disallow' => [ 'action' => 'disallow', 'parameters' => [ 'abusefilter-disallow' ] ]
114: [ 'warn' => [ 'abusefilter-warning-cx' ] ],
118: 'parameters' => [ 'abusefilter-warning-cx' ],
119: 'messageHtml' => wfMessage( 'abusefilter-warning-cx' )
142: [ 'disallow' => [ 'abusefilter-disallow' ], 'degroup' => [] ],
144: 'disallow' => [ 'action' => 'disallow', 'parameters' => [ 'abusefilter-disallow' ] ],
178: [ 'disallow' => [ 'abusefilter-disallow-cx' ] ],
180: 'disallow' => [ 'action' => 'disallow', 'parameters' => [ 'abusefilter-disallow-cx' ] ]
186: [ 'warn' => [ 'abusefilter-warning-cx2' ] ],
190: 'parameters' => [ 'abusefilter-warning-cx2' ],
191: 'messageHtml' => wfMessage( 'abusefilter-warning-cx2' )
242: [ 'disallow' => [ 'abusefilter-disallow-cx2' ] ],