MantisBT's admin/test_langs.php script reports the following errors

Retrieving language files from '/home/dregad/dev/mantisbt/plugins/Source/lang/' | 6 files found
Testing 'strings_english.txt' | ERRORS

• Line 110: $s_plugin_Source_enable_linking contains unsupported or invalid tags or attributes.

Retrieving language files from '/home/dregad/dev/mantisbt/plugins/SourceBitBucket/lang/' | 4 files found
Testing 'strings_english.txt' | ERRORS

• Line 15: $s_plugin_SourceBitBucket_repo_authorization_failed contains unsupported or invalid tags or attributes.

Retrieving language files from '/home/dregad/dev/mantisbt/plugins/SourceGithub/lang/' | 5 files found
Testing 'strings_english.txt' | ERRORS

• Line 31: $s_plugin_SourceGithub_repo_authorization_failed contains unsupported or invalid tags or attributes.

Retrieving language files from '/home/dregad/dev/mantisbt/plugins/SourceGitlab/lang/' | 3 files found
Testing 'strings_english.txt' | ERRORS

• Line 14: $s_plugin_SourceGitlab_hub_reponame contains unsupported or invalid tags or attributes.
• Line 14: htmlParseEntityRef: no name in Entity for string $s_plugin_SourceGitlab_hub_reponame

Retrieving language files from '/home/dregad/dev/mantisbt/plugins/SourceWebSVN/lang/' | 6 files found
Testing 'strings_english.txt' | ERRORS

• Line 12: $s_plugin_SourceWebSVN_websvn_multiviews contains unsupported or invalid tags or attributes.