Polylang non translatable custom taxonomy

It seems that the plugin Media Library Assistant is deliberately setting its custom taxonomy category_attachment as translatable by means of configuration file wpml-config.xml. Therefore changing the line

<taxonomy translate="1">attachment_category</taxonomy>

to

<taxonomy translate="0">attachment_category</taxonomy>

should do the trick. However I did not try myself because I’m not sure of what happens to existing taxonomy terms having a language specification.